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PoliceResearchResearch

GroupGroup

Crime Detection &Prevention Series

Paper 65

LocalCrime

Analysis

Tim ReadDick Oldfield

LOCAL CRIME ANALYSISTim Read

Dick Oldfield

POLICE RESEARCH GROUPCRIME DETECTION AND PREVENTION SERIES: PAPER NO 65

LONDON: HOME OFFICE POLICE DEPARTMENT

Editor: Barry WebbHome Office Police Research Group

50 Queen Anne’s GateLondon SW1H 9AT

Police Research Group: Crime Detection and Prevention Series

The Home Office Police Research Group (PRG) was formed in 1992 to carry outand manage research relevant to the work of the police service. The terms ofreference for the Group include the requirement to identify and disseminate goodpolicing practice.

The Crime Detection and Prevention Series follows on from the Crime PreventionUnit papers, a series which has been published by the Home Office since 1983. Therecognition that effective crime strategies will often involve both crime preventionand crime investigation, however, has led to the scope of this series beingbroadened. This new series will present research material on both crime preventionand crime detection in a way that will inform policy and practice throughout thepolice service.

A parallel series of papers on resource management and organisational issues is alsopublished by PRG, as is a periodical on policing research called ‘Focus’.

ISBN 1-85893-431-1

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© Crown Copyright 1995First Published 1995

‘Crime analysis’ is not a new concept. Police officers have always made theirown assessments about, for example, which areas or hours of the day are busierin crime terms. Increasingly, however, police forces are being encouraged toundertake crime analysis on a more organised and systematic basis.

The National Strategy for Police Information Systems (NSPIS) whichoutlines the principles that should guide the future development of policeinformation technology, identifies crime pattern analysis (CPA) as one of the38 applications required to support the objectives and activities of the policeservice. NSPIS does not, however, include the CPA application amongst itstop priority areas. It is seen as a medium-term priority, and linked to thedevelopment of a national Crime and Incident Reporting System.

In the interim, there is a need to provide guidance to police forces on theissues they need to address and the facilities required from a computer systemto undertake crime analysis. This report provides such guidance in relationto a specific area of crime analysis: the analysis of high volume crime at adivisional or sub-divisional level.

I M BURNSDeputy Under Secretary of StateHome Office, Police DepartmentJuly 1995

Foreword

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We would like to thank the following people for the assistance theyprovided during this project:

Inspector Mike Barron (Merseyside Police Force)Sergeant Marty Byrne (Northumbria Police)Chief Inspector Bill Croft (Home Office Crime Prevention Centre)Sergeant Paul GibbonChief Inspector Brian Gresty (Merseyside Police)Jane Hirst (Police Research Group)George Houghton (Police Research Group)Sergeant David Howe (Metropolitan Police)Jim IngramSimon Jones (Home Office Crime Prevention Centre)Constable John Kelly (West Midlands Police)Chief Inspector Bob LampardSuperintendent Ian Lynch (Northumbria Police)Superintendent Gil Oxley (West Midlands Police)Sergeant Martin Pearson (Metropolitan Police)Detective Chief Superintendent Linsey Reynolds (PAG IT)Constable Caroline Sunderland (West Yorkshire Police)Sergeant Keith Taylor (Merseyside Police)Mike Taylor (Police Research Group)Barry Webb (Police Research Group)

We would also like to thank all those who attended the LCA workshop atthe Police Staff College, Bramshill in June 1994.

Lastly, we are indebted to Professor Ken Pease (Huddersfield University) forhis assistance during the course of the project and for agreeing to referee thisreport.

The Authors

Tim Read and Dick Oldfield are members of the Home Office PoliceResearch Group.

Acknowledgements

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Recently both the Audit Commission and Her Majesty’s Inspectorate ofConstabulary (HMIC) have been encouraging police forces to undertakeCrime Pattern analysis (CPA). However, currently there is a great deal ofconfusion amongst police forces about precisely what is meant by CPA, andlittle guidance exists for forces about how they should undertake this analysis.

This report aims to provide the police with guidance on one particular areaof CPA: Local Crime analysis (LCA). The term ‘Local Crime analysis’ hasbeen coined to describe the analysis at a local level (typically divisional orsub-divisional) of high volume crime - including burglary, theft of/frommotor vehicles and criminal damage.

The term ‘crime analysis’ covers a broad range of different analytictechniques. At a divisional or sub-divisional level police officers are going tobe interested in a variety of different types of analyses, and a variety ofdifferent outputs from LCA. Therefore LCA is considered in relation tospecific areas of police work; crime prevention, repeat victimisation, problemoriented policing, and proactive policing. Using the definition of crimeanalysis developed by the Trevi working party, the report identifies the formsof analysis which are relevant to the local analysis of high volume crime.The report then describes the overall patterns that may be sought locally:

Crime patterns - the nature and distribution of crime within an area:Crime trends - significant changes in an area’s crime pattern over time:Crime clusters - groups of crimes linked through similar characteristics:Crime series - crimes with common offenders.

This report also provides guidance to forces about the practical issues theyneed to consider before undertaking LCA. These fall into two main areas -issues relating to data, and analytical issues. The chapter dealing with theformer examines the type of data that may be used for analysis, possiblesources for this data (both inside and outside the police force), and problemsthat may arise in ensuring its quality. This chapter also considers thenecessity of being able to exchange data between LCA systems at both anintra- and inter-force level.

The section on analytical issues is split into two parts; temporal analysis, andspatial analysis. The first examines the use of time as a variable in theanalysis of high volume crime, and some of the difficulties this poses. Thesection on spatial analysis considers the role played by mapping and

Executive summary

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geographical information systems in LCA. Issues covered include the geo-coding of data for analysis, the level of detail required for mapping, and howthis can be tailored to meet different analytic requirements. It also containsa brief examination of the applicatiosn of expert systems and predictivealgorithms to LCA systems. This is followed by a section that looks at thedissemination of output from LCA, and the training and support needed bysuch systems.

Overall the report stresses that, in order to undertake LCA successfully,police forces must first be clear about their aims and objectives in performingthe analysis. The development of a detailed and accurate user specificationfor an LCA system is central to the success of the venture. At a strategiclevel this involves questions such as why the analysis is being undertaken,what form of analysis is required to support these aims, who the users of theoutput are going to be, and what form of output they require. Thesedecisions will have an obvious ‘knock-on’ impact by determining the moreprosaic aspects of LCA; which data variables need to be collected, theirsources, who is to perform the analysis, where the facility should be sited,whether there is a need to map the data, and so on. With this in mind, thesections of the report which cover data, analysis, and general issues contain anumber of detailed questions designed to assist forces in the development ofa user specification, and of evaluating to what extent commercial LCAsystems meet their requirements.

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Page

Foreword iii

Acknowledgements iv

Executive Summary v

List of Tables ix

1. Local crime analysis: an introduction 1

2. The application of local crime analysis 7

Local crime analysis and problem-oriented policing 8Local crime analysis and crime prevention 9Local crime analysis and repeat victimisation 11Local crime analysis and ‘proactive’ policing: resource allocation 11Local crime analysis and ‘proactive’ policing: targeting offenders 13

3. Collecting the data 16

Data sources 16Type of data 18Data quality 19Data compatibility 21Database facilities 22

4. Analysing the data 23

Conducting searches 23Creating tables 24Statistical analysis 25Temporal analysis 26Spatial analysis 27

Contents

PageMapping facilities 29Level of geographical data required 29Displaying and manipulating data 30Costs 31‘Hot Spot’ analysis and predictive facilities 31Expert systems 33

5. General issues 35

Dissemination 35Training 36Support for local crime analysis systems 36

6. Conclusions and recommendations 39

Current use of local crime analysis by forces 39Recommendations 40

References 42

Appendix A: The Trevi definition of crime analysis 45

Appendix B: Local crime analysis checklist 47

Appendix C: Local crime analysis contact list 59

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List of Tables

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Table Number Caption Page

Table 1 Potential users of output from local crime analysis 4

LOCAL CRIME ANALYSIS: AN INTRODUCTION

1. Local Crime Analysis: an introduction

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The 1993 Audit Commission report ‘Helping with enquiries: Tackling CrimeEffectively’ suggested that Crime Pattern Analysis (CPA) was a “keytechnique which can be effective against prolific criminals”. This supportechoes the message that Her Majesty’s Inspectorate of Constabulary has beendelivering to police forces during the course of its inspection process, thatpolice forces must be able to undertake CPA.

However, whilst, in general terms, there is consensus that the police shouldbe undertaking CPA, there has been little attempt to define the term, andeven less guidance available to the police about how they should set aboutundertaking it. In part this confusion arises from the lack of precisionemployed in discussions about CPA. The terms ‘crime pattern analysis’ and‘crime analysis’ are often employed as if they have clearly understoodmeanings; indeed they are often used interchangeably.

In reality they are best conceived as generic terms. To illustrate this pointmore clearly, the definition of crime analysis produced by the TREVI sub-committee (since superseded by a sub-committee of the K4 Co-ordinatingCommittee), designed to provide a European standard, identifies eightdifferent forms of crime analysis. These eight components, shown inappendix A, reflect the range of circumstances in, and purposes for which,the police may wish to undertake ‘crime analysis’. For example, case analysis(establishing the course of events immediately before, during, and after, aserious offence) is clearly different than crime pattern analysis (identifyingthe nature and scale of crime within a particular area), yet both are forms ofcrime analysis.

This report is concerned with the application of crime analysis to onespecific area of police work: the analysis of high volume crime at a local,either divisional or sub-divisional, level. The term Local Crime Analysis(LCA) has been coined to describe this area of analysis. The focus of thisreport reflects the fact that this type of crime accounts for the majority ofdemand on the police, and that there is increasing interest in the ways thatthe application of crime analysis techniques to high volume crime can assistthe police in managing this demand and in solving these offences.

In general terms, whatever the specific focus of the analysis, LCA is likely tobe concerned with the characteristics of the offence rather than the offender.In addition the analysis usually involves looking at crime in aggregate ratherthan in isolation. Where it focuses upon the offence, LCA can be divided

into three subgroups: analysis for management information, crime clusteranalysis, and crime trend analysis.

Analysis for management information

This is the most basic form of LCA. It involves the analysis of high volumecrime data locally in order to obtain an understanding of the pattern of crimewithin a defined area. The purpose of the analysis is to facilitate general staffand resource management by matching resources to the identified patterns.

Crime trend analysis

A crime trend is defined as a significant change in the nature of selectedcrime types within a defined geographical area and time period. The analysisis concerned with changes in the fundamental crime pattern, and involvescomparisons of aggregated crime data sets over time. Again this is mostlikely to be useful for strategic planning and resource allocation.

Crime cluster analysis

This involves identifying a group of crimes with similar characteristics. Tobe of maximum use to the police the area of commonality shoulddifferentiate the identified crimes from the majority. The crime clusters canbe categorised into the type of crime committed, the way the crime wascommitted, the time committed, type of items stolen, the location of thecrime, the type of victim and so on. Although this type of analysis isdescribed as being ‘criminal incident’ based, data may also be available onthe offender. Studies to identify repeat victimisation would fall within thiscategory.

Comparative case analysis

Comparative case analysis is the one type of analysis within LCA which is asconcerned with offender as offence details. Although similar in somerespects to crime cluster analysis, (both seek to identify a group of offenceswith similar characteristics), comparative case analysis goes further in aimingto identify whether these offences were committed by the same offender orgroup of offenders. This type of analysis can be used to identify possiblesuspects of a crime series by linking the output from crime recording systemsor command and control systems with intelligence data relating to modus


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operandi (MO) and personal descriptions of known criminals. This is theform of analysis that the Audit Commission have been encouraging policeforces to undertake in adopting a proactive approach to dealing with highvolume crime.

There are a number of uses for crime analysis at a local level; to plan resourceallocation, provide management information, identify crime series, designand evaluate crime prevention schemes, or inform participants in partnership approaches (neighbourhood watch schemes and local authoritiesfor example). It is important to emphasise that police officers’ and civilians’particular requirements from crime analysis will be coloured by the type offunction that they perform within the service. Thus, a beat officer may usecrime analysis to obtain a better understanding of the distribution of crimeon his or her beat. Local management may require a similar type of analysis,but at an area level, or over a longer time period, in order to assist withresource allocation. By contrast, a Local Intelligence Officer may requireanalysis of a different form, in order to establish series of crimes linked to acommon offender.

Table 1 provides a list of the potential users of crime analysis at a local level,and the type of analysis they might undertake.


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Local users of LCA Uses for LCA

Crime Prevention Officer Identification of patterns of crime, evaluation ofcrime prevention initiatives, supporting analysis forcrime prevention proposals.

Local Intelligence Officer Knowledge of activity in area, identification of seriesof crime, matching of MO details with knownoffenders, identification of repeat victimisation.

Uniformed Officers Knowledge of activity in and around beat,identification of crime hot-spots’ on beat.

Duty Sergeant Material for shift briefings and to assist in deployment of resources.

CID/Specialist Squads Targeting of crime series, occasional identification ofsuspects, assistance during interviews of suspects,identification of stolen property, collated details ofcrimes under investigation.

Basic Command Unit Knowledge of activity in and around sub-Management division, identification of emerging problems for

focused policing, management information for BCUresources, dissemination of good practice (crimeprevention).

Other Agencies Planning, monitoring & management of activities.

(adapted from Oldfield 1992)


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Table 1: Potential users of products from LCA

The type of analysis that is performed, and the data that are collected, willvary depending on the task undertaken. As a result there is a need forflexible, low-cost LCA systems which the police can tailor to reflect localdemands. While these systems may only offer a short-term solution to forces’overall crime analysis requirements, particularly bearing in mind thedevelopment of the national CPA application, there is still the need toprovide guidance on the issues surrounding the local analysis of high volumeoffences. In addition it is important that the dialogue that attends thedevelopment of the national CPA facility is informed by local experiencewith low-cost LCA systems and awareness of the potential benefits of crimeanalysis.

The next section of this report, ‘the application of local crime analysis’,identifies a number of broad areas where LCA is likely to be of benefit to thepolice. It covers areas such as problem oriented policing, proactive policing,the identification of repeat victimisation, -and the support of crimeprevention initiatives, and examines the role for LCA in these areas.

Sections three, four and five of this report consider the factors that forcesneed to consider in seeking to undertake LCA in detail, and which arepulled together in the LCA ‘checklist’ in appendix B. These sections coverissues such as the type and quality of data required for LCA, sources for thisdata, the type of analysis to be undertaken, the mapping of data, and thetraining and support required for LCA.

In order to undertake LCA successfully it is important that police forces have access to a computer system that meets their analytic requirements. To this end, sections three, four and five contain a number of questionsaimed directly at LCA systems. These questions reflect the Police ResearchGroup’s perception of what the police service should require from an LCAsystem. They provide the police with a means of developing a LCA userspecification that reflects their local needs, and thus the ability to evaluatecommercially available software. This section concludes with the box belowwhich prompts forces to consider the uses to which they wish to apply LCA.


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Which of the following is LCA to be used for:-

Identification of patterns of crime?Management information/crime accounting?Identification of emerging problems for focused policing?Identification of crime/incident ‘hot-spots’?Identification of repeat victimisation?Identification of crime series/repeat offenders?Evaluation of police activities/initiatives?


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Research has shown that crime is seldom randomly distributed across an area, rather there are marked geographical and temporal skews in thepatterning of offence locations, often varying according to the type of crime.For example Sherman found, in a study of telephone calls from the public tothe police in Minneapolis, “substantial concentrations of all police calls, andespecially calls for predatory crime, in relatively few ‘hot spots’. Just overhalf (50.4%) of all calls to the police for which cars were dispatched went toa mere 3.3 percent of all addresses and intersections” (Sherman, 1989).

Similarly the temporal distribution of crime is likely to be skewed, whetherthis be by time of day, day of the week or across seasons. Poyner and Webb(1992) found, in a study of street theft in Birmingham that offences tendedto occur on specific days (Tuesday, Friday and Saturday), and on these days,within narrow time bands. In addition, the offences took place mainly in the summer months. A study of telephone calls to Merseyside Police over athree year period indicated that burglary tended to peak in February andMarch, and to be at its lowest level in July and August (Farrell and Pease,1994).

The analysis of crime and incident data, and the identification of ‘crimepatterns’ is clearly of importance to the police. Research into offence andoffender profiling in South Tyneside had the effect of reducing houseburglaries by as much as fifty percent. By combining computerised analysis of crime recorded data with offender profiling techniques it was feasible forthe local intelligence officer to identify potential suspects and to usestatistical information to target investigations and covert operations. Thecollection of more detailed information on the characteristics of crimes (typeof property attacked, architectural features, point and method of entry,weapons or tools used, and property stolen) also allowed the evaluation oftarget-hardening initiatives and better direction of crime prevention officersas a result (Dale and Lynch, 1994).

The remainder of this section illustrates the central role of LCA in four key,and developing, areas of policing activity:- problem oriented policing, crimeprevention, repeat victimisation, and proactive policing.

THE APPLICATION OF LOCAL CRIME ANSLYSIS

2. The application of local crime analysis

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Local crime analysis and problem-oriented policing

In general terms LCA aims to address the following issues, regardless of thespecific context in which the analysis is undertaken:-

– to identify an area’s crime problems through the analysis of data;

– to raise the level of awareness and understanding of the crime problemswithin an area; and

– to assist in the development of appropriate responses to those problemsthat are of concern.

The use of LCA to identify crime problems locally, and to developappropriate responses is influenced by the concept of ‘problem-orientedpolicing’, advanced by Herman Goldstein. This approach argues that policework should “begin with an analysis of each of the varied problems policehandle and only then proceed to establish the most effective response”(Goldstein, 1990). Problem oriented policing suggests that the police shouldattempt to define and address these problems, to “group incidents asproblems” by identifying the relationships that exist between these incidents, including similarities of behaviour, location, and people involved.

This approach is a response to the traditional reactive model of policingwhich measures the success of police officers in terms of the speed andefficiency with ‘which they deal with the incidents assigned to them. As aresult, it is claimed, incidents are usually handled as isolated events, andconnections seldom made between them.

The definition of ‘problem’ is left deliberately open by Goldstein;- “a clusterof similar, related, or recurring incidents rather than a single incident, asubstantive community concern, or a unit of police business”. This reflectsthe variety of circumstances in which the approach can be employed (citedexamples range from addressing problems of domestic violence or drink-driving to robberies on a specific street to disorder in a particular car park).Incidents may be grouped according to a number of characteristics:-behaviour (usually the type of offence), territory (concentration of theproblem in a given area), persons (either offender or victim) and the time ofthe problem (time of day, day of week or season).


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Crime analysis plays a central role within problem oriented policing. “In apolice agency in which individual officers may not know what has occurredoutside the areas in which they work or during periods when they are not onduty, crime analysis has been the primary means for pooling information thatmay help solve crimes”. In order to deal with the identified problem, itscharacteristics and contributing factors should be examined in detail. Thismay entail collecting information about offenders and/or victims; the time ofoccurrence, location and other details of the physical environment; thehistory of the current problem; the motivations, gains and losses of involvedparties; the apparent (and hidden) causes and competing interests; and theresults of current responses. It is only once this information has beencollected and analysed that an effective response to the problem can bedevised and implemented.

Local crime analysis and crime prevention

The ‘problem oriented’ approach has had a marked impact in the crimeprevention field. In his paper ‘Getting the best out of Crime Analysis’ PaulEkblom advocates a problem oriented approach to identify and determinesolutions to specific, often local, crime problems. He describes the‘preventive process’ as a five-stage sequence of activities, within the overall,continuous monitoring of crime:

1. Obtaining data on crime problems

2. Analysis and interpretation of data

3. Devising preventive strategies

4. Implementation

5. Evaluation

Clearly crime analysis plays a central role in this process. Indeed the studyprovides a comprehensive account of the utility of crime analysis throughoutthe course of a crime prevention initiative. The process begins with thecollection of data likely to be of use in crime analysis, which may beextracted from existing information systems, or generated specifically for the


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analysis. The data then has to be structured for analysis. Analysis involvesthe identification of the patterns, clusters and trends identified above.Ekblom identifies a number of patterns that may emerge:

One way patterns where one variable carries information for guiding(main effects) preventive strategies, ie the occurrence of an

offence over time.

Two way patterns where an association is established between two(associations) variables, normally found by cross-tabulation.

Three way patterns which occur when an association between two(interactions) variables varies with the stage of a third variable.

Ekblom cites the example of street attacks, wherethe likelihood of the victim being injured dependson the age of the assailant (association), and is also influenced by a third variable, the age of thevictim.

The analysis concludes when a clear and consistent picture of the crimeproblem is generated. The final part of the process involves placing theidentified problem in a wider context, taking into account criminological,social and demographic factors that may help to explain it. The informationthat emerges can then be disseminated to he relevant parties within thepolice force to allow the development and implementation of appropriateresponses to the problem. It should be stressed that while Ekblom’s reportfocuses upon the role of crime analysis in the crime prevention field, theproblem-solving process he describes is applicable to other forms of localcrime analysis.

Subsequent work in the crime prevention field has built upon the ‘problemoriented’ approach. For example, Berry and Carter have described amethodology for the evaluation of crime prevention initiatives whichconforms closely to the problem-oriented model. They stress the importanceof analysis in determining the nature and extent of the problem, in definingthe objectives of the initiative, and evaluating its effectiveness (Berry andCarter, 1992).


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Local crime analysis and repeat victimisation

Recent interest in the field of repeat victimisation has indicated a furtherarea for crime analysis. One study found that once a house had been burgled, its chance of repeat victimisation was four times the rate of housesthat had not been burgled before (Forrester et al, 1988). Similarly the 1992British Crime Survey found that 8% of the victims of motor vehicle theftaccounted for 22% of incidents surveyed. This pattern of repeatvictimisation has been shown to apply across a range of offences; racialattacks, domestic violence, crime against small businesses, crime on industrial estates, bullying, school burglary and property crime (Bridgemanand Sampson, 1994).

The realisation that “victimisation is a good predictor of victimisation”across a range of crimes has obvious ramifications for local crime analysis.Farrell and Pease (1994) suggest that the first step in developing a crimeprevention perspective for repeat victimisation “is locally to establish thepatterns of repeat victimisation prevailing in as much detail as the currentpolice command and control system will permit”. Once instances of repeatvictimisation have been identified by crime analysis then strategies toprevent subsequent victimisation can be developed.

The application of crime analysis to repeat victimisation indicates that thedistinction between the reactive (ie identification of crime trends, the spatialdistribution of crime, or repeat victimisation) and proactive use of crimepattern analysis (comparative case analysis in the Audit Commission’sassessment) is of limited practical use. The identification of incidents ofrepeat victimisation through reactive analysis allows police forces to predictwhere future victimisation is likely to take place, and to develop proactivestrategies.

Local crime analysis and proactive policing: resource allocation

Demand from the public for police services has increased at a faster rate thanhave police resources (Audit Commission, 1993). As a result, police forceshave begun to introduce methods of prioritising and managing their responseto this demand. For example, call-grading schemes have been introduced,where the form of the initial police response is determined by the nature ofthe call. A typical scheme will grade calls as requiring an immediateresponse, a delayed response, a response by appointment, and no response.


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Forces have also begun to introduce mechanisms to manage demand and itssubsequent investigation, such as crime desks, dedicated crime lines and helpdesks. A common assumption behind these schemes is that, where policeresources are limited, it is not feasible to deploy police officers to visit everycrime scene and complete a crime report.

In these circumstances there has been much emphasis, not least from theAudit Commission and HMIC, on the need for the development ofproactive strategies by the police, utilising crime analysis to identify suitabletargets for police action. It is suggested that, through crime analysis, theminor crimes that the police are unable to investigate in person are stillincluded in the development of proactive policing strategies. In the absenceof police deployment, and with the increased use of the telephone to reportand record certain types of crime, crime analysis, often termed ‘staticinvestigation’, may provide the sole means of investigating and combatingcertain types of crime.

Local crime analysis therefore offers an alternative to the stark dichotomy ofscreening crimes ‘in’ and ‘out’ of investigation. If police forces are able to useLCA to ‘investigate’ high volume crime this may also allay public concernsthat have arisen as a result of decreasing levels of deployment of policeofficers for these offences. The supposition here is that if crime analysis wereto be routinely undertaken on these offences then the screening decisioncould more accurately be depicted as a filter in the investigative process,rather than marking its end for the vast majority of cases.

Research on crime screening, however, suggests that it is often the quality ofthe information collected on the crime report that determines whether ornot the case will be allocated for further investigation (Gill et al,forthcoming). Clearly, if data deficiencies determine whether the case hasbeen screened ‘in’ or ‘out’ they are also going to have an impact upon thetype of analysis that can be subsequently undertaken, and the value of theoutput from this analysis. Similarly the research discovered that there was agreat deal of confusion, and little guidance as to precisely how the ‘staticinvestigation’ of this, typically high volume, crime was carried out. It isimportant that crime analysis is not viewed solely as a palliative to publicconcerns about decreased deployment of police officers to investigate certaincategories of high volume crime. Should this be the case, and LCA be


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employed on crimes where there is insufficient data to enable comprehensiveanalysis, or in circumstances where the purpose of the analysis is unclear,then the value of LCA is likely to be undermined.

A recent paper evaluating anti-burglary strategies in three forces states thatcrime pattern analysis can “yield information about the likely location andtimes of high volume crime” and can therefore be used to guide thedeployment of resources (Stockdale and Gresham, 1995). The authorssuggest, however, that ‘”its potential value has not been fully exploited;staffing levels and distribution of resources sometimes fail to reflect patternsand amount of criminal activity”. The report indicates that, while there is arole for LCA in the identification of local crime patterns and crime trends,and the consequent allocation of resources to match these patterns better,the process needs planning, and resources, for successful implementation.

Local crime analysis and proactive policing: targeting offenders

In the past, the analysis of high volume criminal incident data tended to beoffence rather than offender focused, reactive rather than proactive, andaimed at the development of strategies to counter the incidence of theoffence, rather than the identification of possible offenders. By contrast, theapproach advocated by the Audit Commission is to detect similaritiesbetween crimes that point to the same perpetrator or group of perpetrators(comparative case analysis). The method is simple. “Every offence involvedin the comparison is carefully scrutinized. The individual characteristics ofdifferent crime are described in columns. These columns may cover, forexample, any disguise used, vehicles used for escape, clothing, descriptionsetc. When the characteristics of different crimes are compared, anysimilarities will immediately become apparent” (Minnebo, 1992 (1)).

The training provided by the National Criminal Intelligence Service (NCIS) for crime analysts follows this model. A comparison schedule iscreated (a list of characteristics associated with the crimes being examined)which is then used to identify links between cases (either general or specificmatches). In an exercise on armed robbery these links cover variables suchas the date, time and location of the offence, characteristics of the offender(height, accent, clothing, facial features, hair and belongings), and type ofsecurity vehicle. Matches (and non-matches) across cases are thenconsidered cumulatively to provide an eventual probability weighting of thelikelihood of the same offender(s) being involved in the cases.


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The Audit Commission suggest that comparative case analysis should beapplied to high volume crime and that, in the case of burglary for example,crimes could be linked on the basis of common characteristics such as themeans of entry, time of day that the crime occurred, types of items stolen andso on. However, care needs to be exercised when seeking to establish pointsof similarity for high volume crimes which might indicate a criminalhallmark. Data which is collected during the course of an investigation intoa serious crime is likely to be far more detailed than the data available to thepolice in relation to high volume crimes, unless the information held on thecrime recording system is supplemented by criminal intelligence or forensicdetails. With high volume crime, white there may be some MOs that aresufficiently uncommon to provide an obvious link between offences andknown offenders, in many cases the MO, or at least the way the MO isrecorded, is likely to be so common as to make case linking through thisvariable alone impossible.

There is an assumption in the Audit Commission’s report ‘Helping withEnquiries..’ that an offender who commits offences such as burglary or theftfrom motor vehicles will always offend in a similar manner. Some support for this view has emerged from research undertaken by Northumbria Policelooking at the MOs employed by house-burglars arrested since January 1993.Their findings indicated that 95% of these offenders retained the same MO,and that three quarters of them carried house-breaking instruments. Theseresults could, however, have arisen as a result of bias in the sample. Thosewho retained the same MO would be more likely to be identified, andarrested, than those whose MO evolved. A self-reporting study on car-theftprovides evidence to support this hypothesis. A third of those interviewedaltered the means by which they broke into and stole the vehicle as theybecame more experienced. “Back then, we used to smash a quarterlightusing a scaffy bar ... but now I like to do the door locks with a screwdriverand rip the alarms off... use a wrench. One time if there was an alarm I usedto leave it, now it’s no problem” (Light et al, 1993).

The above is not to suggest that comparative case analysis should not beapplied locally, but rather to suggest that the technique has to be appliedwith care. A number of LCA packages have already begun to address theissue of comparative case analysis. These systems collect details of convictedor suspected offenders (where known) for offences in the crime analysisdatabase. As a result, crimes can be mapped not only by offencecharacteristics, but by offender characteristics. In short, the system


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endeavours to provide the analyst with a short-cut to the ‘most likely’offenders based on their past criminal behaviour. Indeed one of the LCAsystems has a menu selection that will produce a list of the number of timesan offender has been convicted of an offence using a specific MO.

While there is an obvious appeal to these developments, there is a dangerthat comparative case analysis becomes little more than the unquestioninglinking of offenders to offences through MO. Such developments, andparticularly the reliance on a database of known/suspected offenders, couldbe problematic bearing in mind research studies that indicate the mobility ofoffenders (Farrington and Lambert, 1992) and the relatively transitory nature of persistent offending by juveniles. A recent report found that‘persistent offenders’ (those who committed 10 or more offences in a given 3month period), seldom appeared as persistent offenders in subsequent periods(Hagell and Newburn, 1994).


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This section, and the subsequent two sections of the report examine some ofthe issues that influence the development and operation of an LCA system,and which forces should consider before they begin to evaluate LCA systemsin any detail. The shaded boxes contain detailed questions which the policeshould use in the appraisal of a system to undertake LCA.

Data sources

There are a variety of different data sources available to the police foranalytic purposes. The use of the term ‘Crime Pattern Analysis’ tends toobscure the potential usefulness of non-crime data to the police. Dataalready available to the police can be supplemented by information that hasbeen collected by external organisations. This could include data from localauthorities, retail organisations, crime prevention programmes, or otherpublic sector organisations. The form of the data may also vary. It may beraw data that can be imported into the LCA system and provide morevariables for analysis. Alternatively it may be the results of surveys orprevious research that serve to refine or amend the type of analysisundertaken. An example of the latter might be details of offending ormotivation to offend obtained from research undertaken by the ProbationService with offenders.

Demographic and census data may also be used by the police to interpretcrime patterns in the light of social or economic features (ie levels ofunemployment or the proportion of young people within the area). Thelinking of census data with postcodes has allowed researchers to develop‘small-area’ typologies, “classifications of people according to the types ofareas in which they live” (ie ‘Blue Collar Workers with HighUnemployment’, ‘Young Professionals in Bedsitters’ or ‘Affluent FarmingCommunities’). Geographical Information System (GIS) technology hasallowed the analysis of “the degree of variation among socio-economic groups in the incidence of various conditions”. Within the health field, forexample, the technique (termed ‘geodemographic analysis’) has been used toexamine the incidence of food-poisoning amongst, and the take-up of drugclinics by, various sectors of the population (Brown et al 1991).

While there is the potential for the police to link crime data, and theincidence of specific crime types, with information about the socio/economicstatus of the local population, there are problems inherent in such data.Census data is typically grouped by enumeration districts at a local level, and

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3. Collecting the data

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these may not coincide with the boundaries employed by the police (beats ordivisions). This lack of congruence may cause difficulties in any subsequentanalysis (see Brunsdon 1989).

One of the major problems that has beset LCA systems in the past has beenthe inability of systems to down-load data from other sources, andconsequently the requirement to enter the data for analysis onto thecomputer manually. Clearly this is not an efficient use of police resources,particularly as most police forces are already collecting the data that willprovide the basis for LCA analysis (normally the crime recording system).Therefore it is a prerequisite that an LCA system should be able to down-load data from existing computer systems within the police force

A number of police data sources can be used as the basis for analysis;criminal intelligence, traffic information, property details, nominal databases, incidence data, as well as data taken from the crime recordingsystem. In some cases (domestic violence, for example) police incident logsgive a more accurate indicator of the extent of repeat victimisation than does data taken from the crime recording system because most domesticviolence does not get recorded as a criminal offence. Although there arelimitations to incident log data, its use may allow the identification of aproblem sooner than would be the case with reliance on data from the crimerecording system.

Researchers in Chicago have attempted to take this work one step further indeveloping an ‘Early Warning System’ for gang-related homicides using ageographical crime analysis computer system. The project aims to identifypatterns of nonlethal violence that precede lethal violence inneighbourhoods. In short, based on the assumption that there is arelationship (spatial and temporal) between specific types of gang-relatedcrime and incivilities and subsequent gang homicides, the research uses theincidence of the former to predict where the latter will occur. In order to dothis the project has collected information on lethal and non-lethal crimesfrom Chicago Police, together with data from other agencies about thelocations of parks, schools, public housing, train stations, taverns anddilapidated or abandoned buildings (STAC 1993).

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Can data be captured through an on-line link or by transfer via a magneticmedium?

Can a data link be set up and operated without specialist support?

Are facilities available to design structured data entry forms for manual input?

Can the structured forms support mandatory fields, look up tables, dates/times

and shorthand coded entries?

Are shorthand coded entries automatically expanded into full field entries oninput?

Can the facility retrieve for editing an individual record by its unique crimenumber?

Type of data

Too often in the past the assumption has been made that, in order toundertake effective crime analysis, it is necessary merely to tap into dataalready held on the force’s crime recording system. As a result the analysishas been driven by what was already available, rather than by what was bestsuited to the task in-hand. It is important that, before any analysis isundertaken, careful consideration be given to the type of data required tosupport this analysis.

The type of data that should be collected will depend on the type of analysisthat the police wish to undertake. This relates both to the variables that arecollected, and their format and detail. If the sole purpose of the analysis is toprovide management information about the distribution of crime within thearea then the level of detail already available on the crime recording systemmay suffice. However, the crime recording system may fail to providesufficient detail about the MO employed in an offence to allow comparativecase analysis to be undertaken. As a result the data collected routinely mayhave to be supplemented by additional/more detailed variables. Equally, ifthe analysis is being undertaken as part of a specific project, particularly inconjunction with other agencies, then it may be necessary to tailor thevariables being collected accordingly. An example of the latter is providedby a burglary project in Newton-Ie-Willows, Merseyside where, due to thejoint sponsorship of a burglary project by the local authority, details of

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number of people living in the property and type of property were collectedand analysed by the police (Merseyside Police, 1993). The followingquestions indicate the likely data requirements for an LCA system.

Does the system record the date and time the crime/incident took place?(If the exact time of the crime/incident is not known, can the system displaythe range of possible times, earliest/latest time/date?)

Does the system record the location of the crime/incident?

(‘Location’ may comprise a number of variables, ranging in detail, ie propertynumber/name, street, beat etc. However, it should include a geographicalreference for the crime/incident)

Does the system record details of the crime/incident?

(This should include the characteristics of the offence/incident, the MO,whether the crime was detected, and details of stolen property).

Does the system contain data on offender characteristics

(where known/applicable)?

Does the system provide, where relevant, information on the victim?

Does the system allow a unique victim identifier to be allocated?

Does the system provide/allow access to non-crime data (ie demographic data)?

Data quality

One police force has recently begun comparative case analysis on ‘serial’burglars (individuals convicted of more than four burglaries). When theforce began the analysis it discovered that most of the data it took from thecrime recording system was unsuitable for the analysis; being eitherinaccurate, missing, or of insufficient detail to allow comparison across cases.Similarly, in the anti-burglary project in Newton-le-Willows the officersconcerned found that the data the force routinely collected on burglaries didnot provide the level of detail they required for analysis. As a result aseparate form had to be designed to collect this data. The latter examplealso demonstrates the importance of having an LCA system flexible enoughto take data from outside routine police data sources, if necessary.

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A number of researchers have commented on problems that arise when thedata required for LCA analysis, particularly the address of the offence, isinput in a variable form. Johnston et al (1993) cite the example of‘Reservoir BR Car Park’ which may be recorded at different times as ‘BR CarPar’, ‘Reservoir Car Park’, and so on. The recording of the same address in avariety of different forms will limit the analysis that can be subsequentlyundertaken. Attempts to identify instances of repeat victimisation at anaddress, for example, using a frequencies count, will be compromised becausethe LCA system is likely to treat all these addresses as discrete values andconsequently as different addresses. Similarly, if an LCA system employs agazetteer to generate a reference for mapping purposes, the spelling of anaddress differently from the way it has been recorded in the gazetteer mayprevent the automatic allocation of a geographic reference. In order tominimise these problems police forces should develop rules and conventionsto govern the recording of data subsequently used for LCA (ie rules on theorder of words, permitted abbreviations).

The degree of ‘ownership’ police officers exercise over an LCA system canplay a crucial part in ensuring the quality of the data put into the system.Where officers are persuaded of the benefit of an LCA system, and are ableto use its output operationally, they are more likely to ensure that the data iscollected accurately and in comprehensive detail.

In the project to combat drug-related burglaries at Newton-Ie-Willows thecoordinating officer found that “the quality of the information on the form52 (a form designed to supplement the existing crime reporting sheet) wasnot adequate (for analysis). Distinct briefings of all sections took place butthe best method of education was found to be a ‘hands on’ process. Officerswere encouraged to interrogate the system and see for themselves theinadequacies of their own documentation. Those officers who haveundergone this process have markedly improved their information on form52”. In short, as a result of using the system, officers became aware that itsquality and utility depended on the quality of the data they collected.

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Can data capture/input facilities be easily amended in response to changingrequirements?

Can data be validated against a table of allowable field entries during manualinput?

Can data be validated retrospectively after transfer from another system?

How is the table of valid field entries built and maintained?

Data compatibility

It is important to recognise that crime patterns do not mirror policeboundaries, either locally, or at a force level. Patterns of offending may fallacross divisions, or across forces, and may be lost if there is not the potentialto exchange data between LCA facilities, within and across forces.Currently the interchange of data between, and within, forces is difficultbecause of the variety of different ways crime is recorded, and the lack ofcompatibility between the systems employed.

The ‘local’ remit of this report should not obscure the fact that, with thedevelopment of force-wide facilities aimed at providing a variety of crimeanalysis functions, including the analysis of more serious crime and criminalintelligence data, police forces may need to share data across the force, orobtain data from other forces or national systems. The National Strategy forPolice Information Systems (NSPIS) envisages the eventual creation of anational CPA application with the ability to perform crime analysis at local,force, regional and national levels. This will obviously require theinterchange of data. Thus, in the interim it is important that in developingspecifications for LCA police forces conform to national data standards asthey emerge, and that the LCA systems themselves adhere to NSPIS, whereapplicable, and support the export and import of data.

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Does the LCA system comply with:-

– the national IS/IT strategy

– the force IT strategy?

– crime data standards (eg ACPO CCCIS)?

– general system standards (eg CCTA CC88)?

– the Data Protection Act?

Database facilities

Central to an LCA system is its ability to capture, hold and manipulate thedata required for subsequent analysis. This will be achieved through adatabase facility. The database will need to be flexible as it may need to holdnot only the core set of data identified as necessary to support routine LCA,but also additional data required to assist ad-hoc forms of analysis.

Is an easy-to-use facility provided to set up the database?

Can the database be changed subsequently to include new data fields and fieldentries?

What are the limits of the database facility (maximum number of records, fieldsize, etc.)?

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Conducting searches

Once the LCA database has been set up it will be used by the analyst tosearch the data in order to retrieve individual records or assemble sets ofrecords that correspond to specified criteria (eg crimes that have occurredwithin a certain time-scale, or offences with the same characteristic(s)).This searching through the database is the fundamental component of LCA,allowing the analyst to create sub-sets of data for more detailed subsequentanalysis and to develop hypotheses about patterns of crime, and identifycrime series and crime clusters. It is important that the analyst is notconstrained by the limitations of the LCA database, but is able to developqueries as complex as required, across all variables. For example, if the dataavailable for analysis is un-coded then it is essential that the database has theability to support free-text searches. Similarly the LCA database shouldfacilitate the creation of complex, multi-layered queries in order to allow theanalyst to ‘drill down’ into the data.

Can the facility search on all coded data fields?Does the system support range matching (eg match ranges of dates or times)? Can the facility search text fields for non-coded (free text) entries? Does the system support synonym matching (eg red jumper matches red pullover)?Can search factors be combined using the Boolean operators (and/or/not/nor)? Can search criteria be saved and edited?Can the facility retrieve all records that have been created or amended since aspecified date?Does the searching facility support inexperienced users (eg through pre-definedoptions menu or simple form filling)?Does the facility support expert users (eg by providing shortcuts through menus)?Can the results of searches be displayed as a series of complete records, a list ofsummary details from the records, and within structured report formats?

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Creating tables

It is likely that the analyst will wish to go further than simply identifyingsub-sets of the data that conform to search criteria. Cross-tabulation is seenas an essential technique for LCA, allowing the identification of patterns and relationships between variables. It is essential that an LCA systempossesses the ability to break down and compare crime variables in a tabularform.

Can the facility automatically produce a table showing bow many crimes exist foreach category of a single variable? (eg the system automatically identifies all theMO codes that have been used and lists them showing the number of crimes using them).Can the facility automatically produce a table showing how many crimes exist foreach combination of categories for two or more variables? (eg automaticallytabulating MO codes against beats).Can the facility handle ranges for dates/times etc.? (eg a crime is included if itoccurred between the dates specified)Can a user specify the categories to be tabulated? (eg produce a table with a user-nominated restricted set of MOs.)Can the facility convert the crime numbers into row percentages. columnpercentages and table percentages?Can summary tables be easily exported to other software applications (businessgraphics/statistical package/spreadsheet)?What are the limits of the facility (size of table, number of categories, etc.)?Can suitable print outs be produced by the facility?Are special printing facilities required for the production of large tables?Are there any other special computer system requirements(eg maths co-processor)?Are there any additional costs associated with this element of the system?

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Statistical analysis

In addition to cross-tabulation, statistical tools may be required by the crimeanalyst to interpret the significance of the data being examined. This isparticularly the case where the analyst is seeking to identify crime trends, oris involved in the production of management information statistics. Analysts are unlikely to be experienced statisticians, so such tools must beeasy to use and interpret.

Does the facility support the production of general management informationstatistics? (eg averages and standard deviations).Does the facility support the analysis of variation of crime between two specifiedperiods?Does the facility support the analysis of trends of crime over a specified period? Can the results of this analysis be easily exported into other software applications?Can suitable hard copy be produced by the facility?Are there any special system requirements for this element of the system?Are there any additional costs associated with this element of the system?

Analysts may spend a number of hours interacting with a LCA system beforea pattern, cluster or trend is clearly identified. They will not wish to repeatthat amount of effort every time they wish to re-examine the pattern or showit to somebody else. As a result it is important that the LCA system has theability to ‘record’ the analytic processes that the analyst has followed. This isparticularly important if the analyst is responsible for the production ofsimilar output (ie area crime profiles) on a regular basis.

Are there facilities to record the steps used to carry out the analysis so that it canbe repeated at a later date (eg store the details of a series of cross tabulations forregular use)?

Temporal analysis

The time and date of an offence are key variables for LCA. They are likelyto play a part in most analyses undertaken, whether as a parameter inidentifying crime series or clusters, generating information about crime

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trends (short or long term), or providing an analytic variable for case-linking. Equally it is important, if comparative analysis is to be undertaken,that data is collected over a sufficient time scale to allow these analyses to bemade. Work in the repeat victimisation field has demonstrated theimportance of the time ‘window’ chosen for analysis. For example, if one isattempting to identify repeat crimes, a study of crime in a one week periodwill show virtually no repeat victimisation. “This is because crimes whichare noted during the observed week may be repeats of crime the week before,or may be precursors of crimes in the subsequent week. Even though some ofthe crimes are in fact repeat crimes or linked to future repeat crimes, byresearch of this kind they are observed as ‘single incident’ crimes” (Farrelland Pease, 1993).

If the period of study is increased, or data is collected over a sufficiently longperiod of time, the problem of the time-window will be minimised. In theLCA field the likely requirement to undertake comparative analysis overlong time periods (ie levels of burglary in the first six months of the year,compared to a similar period the previous year) should allay concerns aboutthis problem.

The accuracy of the data collected on the time at which certain high volumecrimes were committed also has an impact on the type of analysis that can beundertaken. While it is relatively easy to record the time an assault tookplace, this is not necessarily the case for a burglary or motor-vehicle crime.When an offence has been committed overnight, or during a period whenthe house was unoccupied, then there will be a range, covering the earliestand latest times possible for the offence to have occurred, rather than asingle definite time. If the offence has taken place while the vehicle owneror occupier was absent for some time (on holiday, for example) the resultmay be a range that covers a period of weeks. This may pose problems forsome types of analyses. If the analyst is looking at the distribution of crimesacross days of the week, or examining whether certain types of offence areoccurring during the day, or at night, the inability to state precisely when acrime took place presents obvious difficulties. In order to compensate forthis some LCA systems have introduced weightings where those crimeswhere the time of commission can be accurately estimated are weighted more heavily than those where the time of commission is more vague (seeBrunsdon, 1989).

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Does the system allow crimes where the time of the offence is known to beweighted for analytical purposes?.

Spatial analysis

The mapping of crime data is not new to the police. Prior to theintroduction of GIS software police forces were using (and some continue touse) manual ‘pin-maps’ to visually display the distribution of crime, and toidentify crime clusters (see, for example, an account of analysis by Hampshire police by Neyroud, 1985). The emergence of GIS systems hasprovided the police with the ability to map and manipulate data sets, orsubsets from data sets, faster, and to link crime data with other data.

Crime data can be mapped in several ways. It can be represented as points ordots on a map. Alternatively data can be represented for areas by shadings orcolours (referred to as choropleth maps, with dark areas usually indicatingareas of low incidence, and light areas indicating high incidence). Finally,data can be indicated as contours, where points of equal value are connectedby lines (contours), and the area between the contour lines are considered ofequal value.

In order to map data for LCA it is necessary to provide it with a geographicalreference (usually a northing and easting). Some forces already geocodetheir crime data, when put onto the crime recording system for example, butif this is not the case, then forces wilt have to consider how, by whom, and towhat level of detail, this referencing is undertaken. In some forces the policeofficers completing the crime report, or the staff inputting the crime data,generate the geographical reference by looking up the location of the crimeon a map and ascribing it a reference point. However, not only is this timeconsuming, but it can also be prone to inaccuracies.

A far better solution is the introduction of a gazetteer which willautomatically assign a grid reference to the crime when the address isentered. Basically, gazetteers operate as ‘look-up’ tables, containing a list ofaddresses with their corresponding reference (geocode). Yet even thissolution has flaws. For example, if the address details on the crime report aredifferent from the address on the gazetteer (ie misspelt, or in a differentorder) it will not be possible to generate a reference for the crime, andmanual intervention will be required.

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There are also problems that arise as a result of the particular nature of policework. Most gazetteers contain details of specific addresses within an area.Difficulties arise when offences occur-at a location other than the specificlocation identified in the gazetteer. For example, a vehicle may be stolen inthe street rather from a house, and may be recovered on waste-ground. Inthese circumstances a gazetteer may not be able to provide a reference for theoffence.

Ordnance Survey (OS) are currently developing a product calledADDRESS-POINT which will eventually provide every postal addressnationally with a grid reference accurate to one metre, together with aunique property reference identifier (to distinguish between those addresseswith a common grid reference, blocks of flats for example). However, theannual cost of ADDRESS-POINT, based on the non-discounted rate of 12pper address (applicable for the first 400,000 addresses) is likely to be welloutside the budget of most divisions!1

Is there a facility to assist with geographical referencing?What address features can be uniquely referenced using the facility (e.g. postcode, street, house number)?

How accurate is the unique reference?How is the referencing facility set up and kept up to date?How does the facility react to an address that it does not have a reference for (a new address in the area, an address outside the area or a misspelling)?How does the facility react to an address that it has more than one reference for(eg more than one ‘12 High Street’ in area)?How does the system deal with a non-addressable incident?

Police forces need to consider the level of accuracy acceptable whengeocoding crime, and again, this level should be determined by the type ofanalysis that is going to be undertaken. Some police forces are content togeocode their crimes by postcode (accurate to 100 metres). If the primaryfocus of LCA is the provision of managment information, and the aim of the analysis is to see the general distribution of crime across the division,then this may be sufficient. However, if the intention is to analyse repeatvictimisation then clearly it will be necessary to identify individual addresseson the map, and to geocode the data more precisely.

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1 Ordnance Survey 1995 Price List.

Mapping facilities

In the past there has been a tendency for police forces to become seduced bythe appeal of GIS. Currently there are innumerable commercial concernsoffering GIS systems to the police for the purpose of ‘crime pattern analysis’.Often these systems have been developed in a non-police environment, butare offered on the basis that they can be ‘tweaked’ to meet policerequirements. Bearing in mind the likely cost of a GIS system it is importantthat police forces plan how the GIS component will be used in analysis, andwhat its benefits are likely to be, before investing in such a system.2

Openshaw suggests that one of the primary reasons for the failure of a GISapplication is the quality of the product specification. “Many users aresimply too vague and either ask the vendor to provide the systemspecification for them or else they do it themselves without any clear idea ofwhat GIS can do and how precisely the final system will perform”(Openshaw et al).

Level of geographical data required

In order to set the location of crimes in context when displayed through themapping facility there needs to be some digitised geographical data (iecomputer based maps) as a background. Digitised geographical data iscommercially available at great levels of detail (eg showing fences and baywindows of houses) - and at great expense. Alternatively maps can bedigitised specifically for the LCA system. Police forces need to consider what level of detail they require when mapping crimes; are they content withan outline of the division showing beat boundaries and major roads, or dothey require a map that shows individual house and garden boundaries? Once again, the decision about the level of map to use should be determinedby the analytic task being undertaken, and the type of data that has beencollected. There is little point in obtaining high resolution maps if the datais geocoded to a lower level. The result will be crimes which, although theyappear to be precisely attached to an individual address, in reality could havebeen located anywhere on a relatively broad area of the map.

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2 See Gunston (1993) for a detailed

account of issues involved in the

purchase of GIS

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Where is the digitised map data obtained from? What is the availability of this data?Are special facilities required to capture the map data (eg digitising tablet orcompact disk drive)?Is there a facility to digitise local boundaries and points of police interest(eg beats, neighbourhood watch areas and local crime generators)?Can different geographical data sets be captured as different layers?What are the physical limits of the system (maximum number of layers, cells,icons, etc.)?

Displaying and manipulating data

At their most basic, all mapping facilities should be able to represent thelocation of individual crimes as a symbol (icon) on the computer based map.However, it is likely that the crime analyst will require a range of additionalfacilities from the mapping application to assist in the display of the data,and to facilitate the investigation and interpretation of patterns, trends andclusters.

Can the mapping facility display crimes as icons overlaid on the map background?Can the shape/size/colour of the icon be linked to specified crime feature(s) (eg ared cross for burglaries through rear doors)?Can the shape/size/colour of the icon be linked to the number of crimes occurring at a single geographic reference (eg larger dots for multiple crimes at asingle location)?What are the limits associated with customising icons in this way? Can the analyst zoom in/out and pan across the map image? Can the crime record be displayed through interaction with the map (ie point and click at the icon to access the associated crime record)?Can crimes be selected and summary details displayed by specifying an area ofinterest on the map (within a user defined radius of a selected point, within a user defined polygon or a pre-defined digitised area)?Can the mapping facility easily combine and display geographically referencednon-crime data sets? Are there any restrictions?

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Can the mapping facility manipulate and display aggregated crime data overspecified areas (eg colour or shade beats according to crime rates)?Are any automatic pattern/trend/cluster identification facilities offered?Can they be shown to work?Are they likely to be of use?

Costs

There ate now GIS systems on the market that offer the police a variety ofdifferent scaled maps within the same package. This means that the level ofthe mapped display can be tailored to fit the specific task being undertaken.In the past the cost of detailed OS maps often proved prohibitive to policeforces, particularly at a divisional or sub-divisional level, and meant thatforces could only afford cheaper maps that did not offer the same detailedresolution. While these costs are now decreasing, and forces may be able toobtain copies of OS digitised maps (with some restrictions) from localauthorities for minimal cost, it is important to recognise that the costs of GISare still high, and GIS technology may need to be thought about as aresource for the whole force rather than the division. Unless consideredcarefully this element of the system can easily put the cost of LCA waybeyond the available budget.

What are the costs for the digitised map data?What are the additional hardware, operating system and software requirements?What additional peripheral equipment is required (eg digitiser, colour printer)?What are their costs for purchase, maintenance and support?What are the training requirements and costs?

‘Hot Spot’ analysis and predictive facilities

The identification and analysis of crime ‘hot-spots’ is not a new area ofanalysis for the police. In an article that describes the failure of a police GIS,Openshaw et al suggest that one of the inherent weaknesses of the systemwas that it was only capable of mapping crime data; the analysis andinterpretation of the data was left entirely to the operator. In thesecircumstances Openshaw suggests that “there is too much data for the

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human being to cope with and the incorporation of appropriate statisticaland geographical analysis procedures is needed to simplify the data analysistask” (Openshaw et al). What is required is a system which would identifyinteresting patterns automatically, which could be subsequently interrogatedin greater detail by the crime analyst.

As Sherman’s 1989 study demonstrated, there are areas where, for a variety of reasons, the incidence of crime is higher (or lower) than probability wouldlead one to expect. An LCA system which could automatically identifycrime ‘hot spots’ with the crime analyst having to perform the barestminimum of functions (typing in the date or offence criteria, for example)has an obvious appeal to police forces. Such a tool could be used to pinpointpolice resources where they were most, or least, needed, to target patrols, orto assist in the placing of closed circuit television cameras.

A number of LCA systems claim to be able to identify these relationshipswithin crime data automatically, and to present these patterns to the analystfor further examination. As well as ‘hot-spot’ analysis these systems may alsooffer predictive facilities (where the future location of crime is predicted onthe basis of previous occurrences).

Brunsdon (1989) suggests that “it is essential that the computer system ...‘hides’ the internal statistical analyses, and presents results in terms of outputmore meaningful to police managers or crime pattern analysts” who,“although experts in the analysis of crime patterns, may not have thetraining to directly apply these statistical methods, or interpret their output”.While the latter is probably true, police officers are likely to remain wary of apredictive system whose logic is ‘hidden’ from them unless, and until, theaccuracy of the algorithms that generate these patterns is provedoperationally. On a rather more fundamental level there remain concernsabout the flexibility of these algorithms, and their ability to take account ofephemeral, localised factors that may impact on crime levels, but which maynot be collected by the LCA database.

Can the algorithms be shown to work reliably with live data?Are any relationships identified by the algorithms likely to be of use or are the vast majority spurious, trivial or false alarms?What are the associated costs for this clement of the system?What is the training requirement for this element of the system?

Expert systems

Similar reservations would seem to apply to the development of ‘expertsystems’ for use in the analysis of high volume crime. An expert system maybe defined as a “computer program which attempts to simulate the way inwhich human experts solve problems. It also seeks to enhance thatperformance, by utilizing the computer’s capacity to carry out many andcomplex operations, simultaneously and rapidly, over a large database”(Gallagher, 1990). The appeal of the expert system to the police is readilyapparent, with its ability to utilise the experience of specialists ininvestigating high volume crimes to generate analytical ‘rules’ that can besubsequently applied to similar types of offences in the absence of thesespecialists.

However, there are a number of problems inherent in the development andapplication of these systems. The American REBES project (REsidentialBurglary Expert System) was launched in the belief that it might be possible“to establish a ‘behavioural fingerprint’ ie a number of discrete actions whichwhen taken together, would point to an individual, or small group ofcriminals, thus making further investigation viable”. These ‘behaviouralfingerprints’ were established by asking experienced burglary detectives tolink, in the form of ‘if - then’ statements, the characteristics of burglaries. Asa result, a number of ‘rules’ were devised that were then used to query aburglary database. At the end of the query the system produced a profile ofthe offender, details of the rules activated during the search, and a list ofsuspects, based upon a comparison of the rules and profiles used (Gallagher,1990).

Once again, the types of analysis claimed for this system rely on theoffending behaviour of an individual remaining constant; identifying ‘likelyoffenders’ for an offence by comparison of an unsolved case with solved cases(or, conversely, indicating cases that a convicted offender may havecommitted), or identifying serial offenders by identifying open cases withsimilar characteristics. The limitations of this approach would appear to berecognised by the designers of REBES in their suggestion that an additionalbenefit of the system is its “ability to compare behaviour of a particularoffender over a number of separate arrests or admissions, and establish theconsistency of his/her criminal behaviour” (Gallagher, 1990). It is not clear,however, how information about possible fluctuations in offending behaviourover time is fed back to REBES and used to amend the analytic rules,

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particularly as the system appears to assume that offending behaviour isconsistent.

A more fundamental concern about the REBES system is the validity of therules upon which the ‘offender profile’ and list of suspects are based. InBaltimore, 397 rules for burglaries were generated by detectives. The ruleswere validated by asking other detectives within the force to indicate theextent to which they agreed with the statement using a five point scale.3 Anystatement that engendered 60% or more disagreement was rejected.

There are obvious concerns that in using one group of detectives to validatethe opinions of others the system does little more than reinforce theprevalent stereotypes that exist within the police about the characteristics ofburglars. Although the system may successfully lead to the apprehension ofan offender it will be biased towards those who conform to those criteriaadvanced by the police, and there is little evidence of the accuracy of thesecriteria. For example, while a rule that proclaims “entry by scam ordeception is the work of gypsies” (one of the original 397 statementsproduced in Baltimore) may lead to the conviction of a number of gypsyburglars, it may say little about the majority of those who commit burglary byartifice. Clearly this raises questions as to how accurate detectives’perceptions about the behaviour of an offender at the scene of a crime are,and on what these perceptions are based.

On what basis are the ‘experts’ who inform the system selected?How are the rules within the expert system generated?Once generated, how are the rules validated?How reliable are the rules that result?How is the system up-dated in the light of subsequent analysis?

ANALYSING THE DATA

34

3 The criteria for the opinion scale

were ‘Strongly Agree’, ‘Agree’,

‘No Opinion’, ‘Disagree’, and

‘Strongly Disagree’ (Gallagher p12)

Dissemination

Output from LCA is likely to be required for a wide variety of purposes, in avariety of different forms. The use of business graphics (ie pie charts, barcharts and graphs etc) to display the results from LCA can assist in theirinterpretation and enhance their impact. Similarly, it may be necessary toincorporate the output from LCA into word-processed text, for example asreports or as briefing documents.

Does the LCA facility have an integral business graphics facility? Can sub-sets of crime data be easily exported and interpreted into a businessgraphics facility?Are there facilities to integrate the products of the analysis (eg lists, tables, charts,graphs and maps) with word processed text?Can suitable print out be produced by the facility (including draft and highquality)?Are there any special system requirements for this element of the system?What are the costs associated with this element of the system?

It is particularly important to be able to disseminate good quality hard-copyfrom the mapping facility of an LCA application. The impact and value ofdetailed digitised maps is diminished if it proves impossible to print qualitypaper copies of what is shown on the computer screen.

Can the facility produce hard copy of maps including clear representation of iconsor shading?Can an operator specify which layers/sets of data are to be printed?Are explanatory details of the output (eg key to icons scale of map, operatoridentity and date of production) automatically included on the hard copy?Are both draft and good quality hard copy available?Are both monochrome and colour printing options available?How long does it take to produce a print-out?Can the size of the print-out be controlled?

GENERAL ISSUES

5. General issues

35

Training

The development of menu-driven LCA systems, and the ability to save andrecall frequently repeated data queries, has led to a decrease in the level ofcomputing expertise required of police officers in order to analyse data.Nevertheless, the importance of training in the LCA field should not beunder-estimated. At present, little training is offered to crime analysts; inthe main they are expected to learn ‘on the job’. As a result it is importantthat LCA systems are designed to be easy to use and require little training.

What is the overall training requirement for the system?

Does the system have any interactive training facilities?.

Can menu structures, screen designs and other interface features be customised tomeet the local requirement?

Does the system have an on-line help facility?

Does the system support both new users and advanced users?

How easy is it to navigate through the elements of the system?

Can each of the analysis facilities support a library of regularly used operations?

Are the system response times adequate for interactive use?

Support for LCA systems

At present it is unlikely that a police force will be able to purchase an system‘off the shelf’ and install it without tailoring it to suit local requirements.The system will requite adaptation to link it to existing computer systemswithin the force, database structures will require amending, and the analyticoutput may need to be developed to meet local requirements. Indeed,Openshaw has suggested that customisation is crucial to the success of a GISsystem.

In addition, once the LCA system is in operation there will be a requirementto support the system, in case of any breakdown. Computerised crimeanalysis is still a relatively new discipline within the police service, and mostpolice forces are currently still deciding on the potential use of, andrequirements from an LCA system. As a result, existing LCA systems arelikely still to be developmental and to evolve further in the future.

GENERAL ISSUES

36

For all the reasons outlined above, it is essential that forces ensure that theLCA supplier offers comprehensive and reliable support for the system. Ifthis is not the case, police forces may find themselves saddled with a systemthat is inflexible, where they cannot obtain prompt support in the event ofbreakdown, and where the supplier has little interest in the continueddevelopment of the system. Too often in the past individual police forceshave developed LCA facilities with local software houses or academicinstitutions. These LCA facilities have subsequently withered on the vinewhen the individuals responsible for the development have moved on.

Commercial suppliers will specify a minimum configuration for the computerhardware required to support the LCA system (eg in terms of speed ofcomputer or size of disk storage). It is important that police forces ensurethat system limitations in terms of the volume of data that can be handled,processing speeds and so on do not fall short of local requirements.

What are the hardware, operating system and software requirements for the LCAfacility?What are the associated purchase, set up, maintenance and support costs? Are all elements available and supported in the UK?What are the training requirements and costs?Are facilities available to assist with data back up, weeding and archiving? What are the other resource costs for the system (eg manpower for data capture,geo-referencing, housekeeping)?

Overall police forces should ask the following basic quest ions of an LCAapplication:-

Is the system sufficiently robust to operate at sub-divisional level?Is the system sufficiently cheap to be implemented at sub-divisional level?Is the system sufficiently supported to be implemented at sub-divisional level?Can the system provide a high level of availability for all routine operations?

GENERAL ISSUES

37

Finally forces must assess the security requirements for their implementationof LCA systems.

Can password security be set up?Can the system limit functionality according to user type (analyst, systemmanager, data inputter, read-only enquiries)?

GENERAL ISSUES

38

Current use of LCA by forces

Currently there are a number of police forces using LCA systems. Thefunctionality, sophistication and cost of these systems varies enormously.Similarly the extent to which they undertake the various functions thatcomprise ‘crime analysis’ differs; some forces utilise systems that provide onlytabular output for crime trend or management information purposes, otherforces (admittedly the minority) have adopted high-cost, networked GISapplications. The genesis of these systems also varies widely. While someforces have adapted commercially available packages, other forces havedeveloped systems internally, or in partnership with academic institutions.

In the past it was probably true to say that, with a few exceptions, theprovision of crime analysis within a force tended to arise as a result of localinitiative or interest, often on the part of divisional or sub-divisionalmanagement. As a result there are a number of forces who currently have arange of different LCA systems operating within the force (one metropolitanforce has at least six separate crime analysis systems within force).

While such a situation smacks of duplication, it has to be remembered thatthese systems developed in the absence of force or national guidance oncrime analysis. In addition it has been the systems developed from localinitiatives that have demonstrated the operational effectiveness of highvolume crime analysis. The predominantly local impetus behind thedevelopment of LCA systems has ensured that the systems tend to be low-cost, and personal-computer based.

A number of police forces, however, are now undertaking force-wide reviewsof their crime analysis requirements encouraged by the focus of the AuditCommission and HMIC on crime analysis. Currently several forces aredeveloping user specifications to meet these requirements. The all-encompassing scope of these reviews, and the likely cost of theirprocurement, mean that they go some way beyond the remit of this piece ofwork.

Nevertheless, these reviews are in their early stages at present, and only aminority of forces are undertaking them, which suggests that there will be arole for open, low-cost, flexible LCA systems in the short term at least.Appendix B of this report provides a list of manufacturers and police forcescontacted during the course of this research. The list is neither definitive

CONCLUSIONS AND RECOMMENDATIONS

6. Conclusions and recommendations

39

nor comprehensive, and should not be construed as constituting a PoliceResearch Group ‘seal of approval’, but gives some idea of the range of systemsthat have been developed to undertake ‘crime analysis’.

Recommendations

This report has not attempted to produce a user specification for an LCAsystem, or provide a detailed appraisal of existing systems because it was feltthat this approach was too prescriptive. Such a specification could not takeinto account the different requirements for LCA that police forces mighthave locally, or the current uses of technology within the force. What it hasdone is to identify the decisions and issues that forces will need to tackle indeciding which LCA systems are right for them. The questions found insections three, four and five of this report, and brought together in appendixB, should be used by the police to inform the development of their userspecification, and thus as a means of evaluating the extent to whichcommercially available LCA packages meet their specific requirements. Thefollowing are some of the key issues which need to be addressed in achievingthis:

☞ In order to produce a robust user specification for LCA the force or(sub)division needs a clear perception of the type of crime analysis itwishes to undertake, the purpose of the analysis, who the users of theoutput will be, and what their output requirements are. All thesedecisions need to be clarified long before they approach themanufacturers of LCA systems.

☞ The type of data collected for LCA should always be dictated by thetype of analysis required, rather than the reverse. Too often in the pastthe form of analysis done by the police has been determined by theform of data held on existing IT systems.

☞ Data taken from crime recording systems may not be sufficient to allowthe force to undertake LCA. Links to alternative data sources, bothwithin and outside the police force, should be established wherenecessary.

☞ LCA systems must have the potential to down-load data from existingdata sources. The manual input of LCA data should be avoidedwherever possible.


40

☞ Police forces should seek to develop conventions to govern therecording of data used for crime analysis to minimise problems in itsinputting and subsequent analysis.

☞ It is essential that data can be interchanged between LCA applications,at an inter- and intra-force level. As a result the police, even at a locallevel, must take account of data standards and the emergent nationalIS/IT strategy in the procurement of LCA systems.

☞ Prior to the purchase of a GIS application, police forces need toidentify their purpose in mapping crime data, and the level ofresolution required as a result. These considerations will haverepercussions in terms of the costs of the system. Where resources formapping are limited links with local authorities, who may already haveaccess to high-resolution digitised maps, may provide a solution.

☞ In purchasing an LCA system police forces should recognise that thearea is relatively new and is still developing. Requirements from LCAsystems are likely to evolve. In these circumstances it is crucial thatthe LCA suppliers are able to provide a high level of support for thepackage, to ensure its continued operation and development.

☞ It is important that police forces identify the training requirementsneeded to undertake LCA. This training should go beyondinstructions on how to operate the LCA system, and must includetraining on the type and purpose of analysis required.


41

Audit Commission (1993) Helping with Enquiries: Tackling Crime Effectively,Audit Commission: Police Paper No 12. London: HMSO.

Audit Commission (1994) Tackling Crime Effectively: Management Handbook.

Berry, G. and Carter, M. (1992) Assessing Crime Prevention Initiatives: TheFirst Steps: Crime Prevention Unit Paper No.31. London: Home Office.

Block, C. R. (1992) Automated Spatial Analysis as a Tool in ViolenceReduction. Unpublished paper presented to Problem-Oriented PolicingConference, Police Executive Research Forum, San Diego, October 16, 1992.

Bridgeman, C. and Sampson, A. (1994) Wise After the Event: TacklingRepeat Victimisation. A Report by the National Board for Crime Prevention.London: Home Office.

Brown, P. J. B., Hirschfield, A. and Batey, P. W. J. (1991) ‘Applications ofGeodemographic Methods in the Analysis of Health Condition IncidenceData’ in Papers in Regional Science: The Journal of the RSAI 70, 3.

Brunsdon, C. F. M. (1989) Spatial Analysis Techniques Applied to Local CrimePatterns. Unpublished, PhD thesis, University of Newcastle upon Tyne.

Dale, A. and Lynch, I. ‘Profiling the burglars’ in Police Review, 3 June 1994.

Ekblom, P. (1987) Getting the Best out of Crime Analysis. Crime PreventionUnit Paper No 10. London: Home Office.

Farrell, G. and Pease, K. (1993) Once Bitten, Twice Bitten: RepeatVictimisation and its Implications for Crime Prevention. Crime Prevention UnitPaper 46, London: Home Office.

Farrell, G. and Pease, K. (1994) ‘Crime Seasonality: Domestic Disputes andResidential Burglary in Merseyside 1988-90’ in British Journal of CriminologyVol 34 No4 Autumn 1994.

Farrington, D. P. and Lambert, S. D. (1992) The Feasibility of a StatisticalApproach to Offender Profiling: Burglary and Violence in Nottinghamshire.Unpublished.

REFERENCES

References

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Forrester, D., Chatterton, M. and Pease, K. (1988) The Kirkholt BurglaryPrevention Project, Rochdale. Crime Prevention Unit Paper 13. London:Home Office.

Gallagher, K. P. (1990) Expert Systems In The U.S.A. Unpublished, ThamesValley Police.

Gill, M., Hart, J., Livingstone, K. and Stevens, J. (forthcoming) Caseallocation and police investigations into burglary and auto crime. Police ResearchSeries. London: Home Office.

Goldstein, H. (1990) Problem-Oriented Policing. New York: McGraw-Hill.

Gunston, M. (1993) Geographic Information Systems: A Buyer’s Guide.London: HMSO.

Hagell, A. and Newburn, T. (1994) Persistent Young Offenders. London:Policy Studies Institute.

Home Office (1994) The National Strategy for Police Information Systems.London: Home Office.

Johnston, V., Shapland, J. and Wiles, P. (1993) Developing Police CrimePrevention: Crime Analysis. Unpublished.

Light, R., Nee, C. and Ingham, H. (1993) Car Theft: The OffendersPerspective. Home Office Research Study 130. London: HMSO.

Merseyside Police. (1993) Evaluation of the Newton-Ie-Willows JointCommunity Safety Initiative, Operation Newburg. Unpublished.

Minnebo, P. (1) (1992) ‘Talking About Crime Analysis’ in van der Heijden, T.and Kolthoff, E. (eds) Crime Analysis: a tool for crime control. Den Haag: BenBaruch.

Minnebo, P. (2) ‘Talking About Crime Analysis’ in RechercheInformatiebulletin. CRI July 1992.

Neyroud, P. W. (1985) Incident Pattern Analysis: the Management of PoliceResources in Preventing Crime. Hampshire Constabulary.

REFERENCES

43

National Criminal Intelligence Service Training Package, Session 19,Comparative Case Analysis.

Oldfield, R. (1992) A Review of Crime Pattern Analysis in the UK PoliceService. Police Research Group, unpublished.

Openshaw, S., Cross, A., Charlton, M. and Brunsdon, C. (undated)Lessons learnt from a Post Mortem of a failed GIS.

Poyner, B. and Webb, B. (1992) ‘Reducing theft from shopping bags in citycenter markets’ in R. V. Clarke (ed) Situational Crime Prevention, SuccessfulCase Studies. New York: Harrow and Heston.

Ratledge, E. C. and Jacoby, J. E. (1989) Handbook on Artificial Intelligenceand Expert Systems in Law Enforcement. New York: Greenwood Press.

Reinier, G. H., Greenlee, M. R., Gibbens, M. H. and Marshall, S. (1977)Crime Analysis in Support of Patrol. National Institute of Law Enforcementand Criminal Justice, Law Enforcement Assistance Administration, UnitedStates Department of Justice.

Sherman, L. W., Gartin, P. R. and Buerger, M. E. (1989) ‘Hot Spots OfPredatory Crime: Routine Activities And The Criminology Of Place’.Criminology, Vol 27, Number 1, Feb 1989.

STAC (1993) ‘An Early Warning System for Violence’ in STAC News,Volume 1, No 1, Winter 1993.

Stockdale, J. E. and Gresham, P. J. (1995) Combating Burglary: Anevaluation of three strategies. Crime Detection and Prevention Series No59.London: Home Office.

REFERENCES

44

The Trevi definition of crime analysis differentiates between two basis typesof analysis; ‘strategic’ and ‘operational’. Types of analysis designed to aid theformation of policy are termed ‘strategic’, while those designed to support theinvestigation of a particular case are termed ‘operational’.

Strategic analysis aims to provide information which can provide a picture ofa phenomenon, and which can identify trends in criminality on whichmanagement can base their decisions. This allows for the initiation of plansof action against emerging crime on a long-term basis, rather than merelyreacting to a single criminal act.

Operational analysis aims to provide an understanding of the informationcollected during a specific investigation. It may involve the identification oflinks between individuals and/or events, an indication of where further workneeds to be undertaken, or an indication of conflicting information.

Eight specific forms of crime analysis are identified.

Strategic forms of analysis

1. Crime Pattern Analysis which attempts to form a picture of the natureand scale of crime in a particular area. The size of the area, or the type andnumber of crimes examined, may vary. Descriptive, or inferential statisticsare used for analysis, which may be supplemented by qualitative material.

2. General Profile Analysis which aims to identify typical characteristics ofperpetrators of certain crimes. There is no set method for general profileanalysis, which tends to involve the combination of judicial informationwith information from “human sciences, experience, and common sense, inorder to arrive at useful principles for police practice”. (The quoted exampleof this technique is its use, by Dutch Customs, to spot suspected drug courierson the basis of factors such as passport, clothing, behaviour, nervousness etc).General profile analyses may focus not only on the offender, but also on thelikely victim of crime.

3. Crime Control Methods Analysis aims to learn from the experiencegained with techniques and tactics used during previous police actions. Inother words, it involves the evaluation of methods and techniquesintroduced with the aim of establishing their future usefulness.

APPENDIX

Appendix A. The Trevi definition of crime analysis

45

Operational forms of analysis

4. Case Analysis attempts to establish the course of events immediatelybefore, during, and after, a serious offence. This involves charting a relevant(offender, victim or witness) individuals’ activities chronologically. Theevolution of the chart, particularly the existence of any areas of confusion oruncertainty, indicates areas for further analysis.

5. Comparative Case Analysis seeks to detect similarities between crimes -that point to the same perpetrator or groups of perpetrators.

6. Offender Group Analysis aims to provide all available information oncontacts between certain individuals contained on police records, andconnect this to their possible involvement in criminal activities. In this typeof analysis a number of diagrammatic techniques will be used; relationaldiagrams, event charts, activity charts and flow charts for money and goods.

7. Specific Profile Analysis which involves constructing a hypotheticalpicture of the perpetrator of a crime on the basis of data from the scene ofthe crime, witnesses’ statements and other available information. (This typeof analysis is perhaps more commonly known by the term OffenderProfiling’).

8. Investigations Analysis involves the study and evaluation of activitiesthat are undertaken within the context of an investigation, with the aim ofrounding off that investigation and of identifying courses of action that havenot been pursued (Minnebo, 1992 [1]).

APPENDIX A

46

What follows is a ‘checklist’ for LCA systems designed to provide guidanceto police forces (and inform software manufacturers) on the functionalityrequired from an LCA system. It is not a technical specification, as it wasfelt that this would be too prescriptive to be of general use to the police, butdeals with the various components that constitute an LCA system; databasefacilities, analytic facilities, mapping facilities, as well as a section coveringgeneral requirements.

The checklist provides a framework to assist with the evaluation of systemsoffered to support the LCA process. For each element a number of questionsare asked to establish how well the system under evaluation will supportLCA and what the accompanying resource commitments are likely to be.

While the checklist is designed to be comprehensive, there may be specificlocal considerations that are not covered in it. These should be added to thechecklist. Equally, any factors that are super-nummary to local requirementsshould be disregarded.

Uses for LCA

Prior to any detailed decisions being taken about the specification of an LCAsystem, it is important that the police identify the purpose(s) for which thesystem will be used.

Which of the following is LCA to be used for:-Identification of patterns of crime?Management information/crime accounting?Identification of emerging problems for focused policing?Identification of crime/incident ‘hot-spots’?Identification of repeat victimisation?Identification of crime series/repeat offenders?Evaluation of police activities/initiatives?

Type of data required for LCA

The type of data collected for LCA will depend on the type of analysis thatthe police wish to undertake. This relates both to the variables that arecollected, and their format and detail. However, the following questionsindicate the likely core data requirements for an LCA system.

APPENDIX B

Appendix B. Local crime analysis checklist

47

Does the system record the date and time the crime/incident took place?(If the exact time of the crime/incident is not known, can the systemdisplay the range of possible times, earliest/latest time/date?,)

Does the system record the location of the crime/incident?(‘Location’ may comprise a number of variables, ranging in detail, ieproperty number/name, street, beat etc, However, it should include ageographical reference for the crime/incident)

Does the system record details of the crime/incident?(This should include the characteristics of the offence/incident, the MO,whether the crime was detected, and details of stolen property).

Does the system contain data on offender characteristics (whereknown/applicable)?

Does the system provide, where relevant, information on the victim?Does the system allow a unique victim identifier to be allocated?Does the system provide/allow access to non-crime data (ie demographic data)?

Database facilities

Central to an LCA system is its ability to capture, hold and manipulatecrime data. This will be achieved through a database facility.

i) How easy is it to set the database up?

There will be some variation in the way that databases are set up to takeaccount of local requirements. The database will need to hold a core set ofdata required for LCA together with any other information required locally.If no facilities are provided for in-force personnel to set the database up thenexpensive specialist support may be required.

Is an easy-to-use facility provided to set up the database?Can the database be changed subsequently to include new data fields and fieldentries?

ii) How easy is it to capture/input data?

There will be a daily requirement to capture crime data and there may be anoccasional requirement to capture supplementary crime data and non-crimedata (e.g. census data). Often some or all of this data will be held already onanother computer system. It is not desirable to duplicate the manual entry ofthis data onto the LCA system, but this may be the only practical methodwhen the system is first installed.

APPENDIX B

48

Can data be captured through an on-line link or by transfer via a magneticmedium?Can a data link be set up and operated without specialist support?Are facilities available to design structured data entry forms for manual input?Can the structured forms support mandatory fields, look up tables, dates/timesand shorthand coded entries?Are shorthand coded entries automatically expanded into full field entries oninput?Can the facility retrieve for editing an individual record by its unique crimenumber?Can data capture/input facilities be easily amended in response to changingrequirements?Can data be validated against a table of allowable field entries during manualinput?Can data be validated retrospectively after transfer from another system? Howis the table of valid field entries built and maintained?

iii) Does the facility assist with geographical referencing?

Many LCA techniques require crimes to be geographically referenced (ieallocated a northing and easting). In a few forces crimes may be alreadygeographically referenced when captured. For the remaining users, anautomated referencing system will provide advantages over the manualreferencing of every crime from a paper map. Gazetteers are viewed as goodsolutions to this problem, whereby a user enters the address of die crime andthe system automatically allocates the appropriate grid reference.

Is there a facility to assist with geographical referencing?What address features can be uniquely referenced using the facility (e.g.postcode, street, house number)?How accurate is the unique reference?How is the referencing facility set up and kept up to date?How does the facility react to an address that it does not have a reference for(a new address in the area, an address outside the area or a misspelling)?How does the facility react to an address that it has more than one referencefor (eg more than one 12 High Street’ in area)? How does the system deal with a non-addressable incident?

APPENDIX B

49

iv) Is adequate functionality for searching the database provided?

The database facility will be used to search the data to retrieve individualrecords or assemble sets of records satisfying some criteria.

Can the facility search on all coded data fields?Does the system support range matching (eg to match ranges of dates ortimes)? Can the facility search text fields for non-coded (free text) entries?Does the system support synonym matching (eg red jumper matches redpullover)?Can search factors be combined using the Boolean operators (and/or/not/nor)?Can search criteria be saved and edited?Can the facility retrieve all records that have been created or amended since aspecified date?Does the searching facility support inexperienced users (eg through pre-definedoptions menu or simple form filling)?Does the facility support expert users (eg by providing shortcuts throughmenus)?Can the results of searches be displayed as a series of complete records, a list ofsummary details from the records and within structured reports?

vi) Can the database facility produce the required outputs?

Analysts will use the database facility to select a sub-set of the crime datawhich they will then wish to export to another analytical facility. (Whetherany real ‘output’ will be required to achieve this export will be dependent onthe architecture of the system.) Output is also required from the databasefacility for print outs.

Can sub-sets of crime data be made avail-able immediately for further analysis(e.g. cross tabulation or mapping)?What standard file transfer formats can be produced by the facility? (eg ASCIIor DBF)What other facilities are available to assist the transfer of data between thedatabase facility and other applications/systems?Can the facility produce print outs of records, lists and structured reports? Are explanatory details of the output (eg summary search criteria, operatoridentity and date of production) automatically included on the print outs?

APPENDIX B

50

vi) What are the resource commitments for the database facility?

Suppliers will specify a minimum configuration for the system required tosupport the database element of an LCA system (eg in terms of speed ofcomputer or size of disk storage). The assumptions made concerning thevolume of data, processing levels and response times must be comparedagainst the local requirement.

What are the hardware, operating system and software requirements for thedatabase facility?What are the associated purchase, set up, maintenance and support costs? Are all elements available and supported in the UK?What are the limits of the database facility (maximum number of records, fieldsize, etc.)?What are the training requirements and costs?Are facilities available to assist with data back up, weeding and archiving? What are the other resource costs for the database element (eg manpower fordata capture, geo- referencing, housekeeping)?

Analysis facilities

The ease with which sub-sets of crime data can be moved between analyticalapplications will have a significant effect on the usability of the system.

i) Can crime data be displayed, manipulated and disseminated in tabulated form?

Cross-tabulation is seen as a ‘bread and butter’ technique for LCA. A facilityis required to break down and compare crime variables in a table to assist inthe identification of patterns and relationships between variables.

Can the facility automatically produce a table showing how many crimes existfor each category of a single variable? (eg the system automatically identifies allthe MO codes that have been used and lists them showing the number ofcrimes using them).Can the facility automatically produce a table showing how many crimes existfor each combination of categories for two or more variables? (eg automaticallytabulating MO codes against beats).Can the facility handle ranges for dates/times etc.? (eg a crime is included if itoccurred between the dates specified).

APPENDIX B

51

Can a user specify the categories to be tabulated? (eg produce a table with auser-nominated restricted set of MOs).Can the facility convert the crime numbers into row percentages, columnpercentages and table percentages?Can summary tables be easily exported to other software applications (businessgraphics/statistical package/spreadsheet)?What are the limits of the facility (size of table, number of categories, etc.)? Can suitable print outs be produced by the facility?Ate special printing facilities requited for the production of large tables?Are there any other special computer system requirements (eg mathscoprocessor)?Are there any additional costs associated with this element of the system? What is the training requirement for this element of the system?

ii) Can crime data be displayed, manipulated and disseminated using simplestatistical techniques?

Statistical tools are required to help analysts interpret the significance ofpatterns, trends and clusters in crime data. Analysts are unlikely to beexperienced statisticians, so such tools must be easy to use and interpret.

Does the facility support the production of general management informationstatistics? (eg averages and standard deviations).Does the facility support the analysis of variation of crime between twospecified periods?Does the system allow crimes where the time of the offence is known to beweighted for analytical purposes?Does the facility support the analysis of trends of crime over a specified period? Can the results of this analysis be easily exported into other softwareapplications?Can suitable hard copy be produced by the facility?Are there any special system requirements for this element of the system?Are there any additional costs associated with this element of the system?What is the training requirement for this element of the system?

iii) Can the results of crime data tabulations and the statistical analysis of crimedata be displayed and disseminated using business graphics tools?

APPENDIX B

52

Business graphics (pie charts, bar charts, graphs etc.) assist with theinterpretation and dissemination of the analysis.

Does the facility have an integral business graphics facility?Can sub-sets of crime data be easily exported and interpreted into a businessgraphics facility?Can suitable print out be produced by the facility (including draft and highquality)?Are there any special system requirements for this element of the system? What are the costs associated with this element of the system? What is the training requirement for this element of the system?

iv) Can the results of analysis be integrated with word processed reports fordissemination?

In many cases the results of an analysis will need to be supported by a writtenreport.

Are the facilities to integrate the products of the analysis (eg lists, tables,charts, graphs and maps) with the word processed text?Are there additional costs associated with this element of the system? What is the training requirement for this element of the system?

v) Are any automatic pattern/trend/cluster identification algorithms offered?

Most analysts use their knowledge of the crime data together with theanalytical tools already mentioned to develop and test hypotheses aboutpatterns, trends and clusters within their data. Some LCA systems claim tobe able to identify these relationships within crime data automatically. Theanalysts are then presented with these apparent patterns to explore further.

Can the algorithms be shown to work reliably with live data?Are any relationships identified by the algorithms likely to be of use or are thevast majority spurious, trivial or false alarms?What are the associated costs for this element of the system?What is the training requirement for this element of the system?

If an ‘expert system’ is required to undertake LCA, the following questionsshould be asked.

APPENDIX B

53

On what basis are the ‘experts’ who inform the system selected?How are the rules within the expert system generated?Once generated, how are the rules validated?.How reliable are the rules that result?How is the system up-dated in the tight of subsequent analysis?

vi) Can the results of an analysis be saved for future reference?

Analysts may spend a number of hours interacting with a LCA system beforea pattern, cluster or trend is clearly identified. They will not wish to repeatthat amount of effort every time they wish to re-examine the pattern or showit to somebody else.

Are there facilities to record the steps used to carry out the analysis so that itcan be repeated at a later date (eg store the details of a series of crosstabulations for regular use)?What is the training requirement for this element of the system?

Mapping Facilities

Although computerised mapping facilities are viewed as another analyticaltechnique for LCA, they deserve particular consideration due to theirpotential resource implications. Indeed the costs are such that GIStechnology may need to be thought about as a corporate resource for thewhole force, rather than trying to justify the investment through LCA alone.

i) How does the mapping facility capture digitised geographical data?

In order to set the location of crimes in context when displayed through themapping facility there needs to be some digitised geographical data (iecomputer based maps) as a background. Digitised geographical data iscommercially available at great levels of detail (eg showing fences and baywindows of houses) - and at great expense. Alternatively maps can bedigitised specifically for the LCA system. The level of detail required willdepend on the type of analysis undertaken.

Where is the digitised map data obtained from?What is the availability of this data?Are special facilities required to capture the map data (eg digitising tablet or

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compact disk drive)?Is there a facility to digitise local boundaries and points of police interest (egbeats, neighbourhood watch areas and local crime generators)?Can different geographical data sets be captured as different layers? What are the physical limits of the system (maximum number of layers, cells,icons, etc.)?

ii) Is adequate functionality provided by the mapping facility?

All mapping facilities should be able to represent the location of individualcrimes as an icon positioned on the background digitised map information.A range of other facilities may be required by the analyst to assist in theinvestigation and interpretation of patterns, trends and clusters.

Can the mapping facility display crimes as icons overlaid on the mapbackground?Can the shape/size/colour of the icon be linked to specified crime feature(s) (ega red cross for burglaries through rear doors)?Can the shape/size/colour of the icon be linked to the number of crimesoccurring at a single geographic reference (eg larger dots for multiple crimes ata single location)?What are the limits associated with customising icons in this way? Can the analyst zoom in/out and pan across the map image? Can the crime record be displayed through interaction with the map (ie pointand click at the icon to access the associated crime record)?Can crimes be selected and summary details displayed by specifying an area ofinterest on the map (within a user defined radius of a selected point, within auser defined polygon or an pre-defined digitised area)?Can the mapping facility manipulate and display aggregated crime data overspecified areas (eg colour or shade beats according to crime rates)?Are any automatic pattern/trend/cluster identification facilities offered?Can they be shown to work?Are they likely to be of use?

iii) Can the mapping facility provide access to other geographically referenceddata sets?

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Occasionally an analyst will want to-combine crime data and othergeographically referenced data (eg local authority boundaries or census data)over a map background

Can the mapping facility easily combine and display geographically referencednon-crime data sets? Are there any restrictions?

iv) Can the mapping facility produce the required Output?

Whereas multi-coloured maps look good on computer screens, good qualityhard copy is required to assist with dissemination.

Can the facility produce hard copy of maps including clear representation oficons or shading?Can an operator specify which layers/sets of data are to be printed?Are explanatory details of the output (eg key to icons, scale of map, operatoridentity and date of production) automatically included on the hard copy?Are both draft and good quality hard copy available?Are both monochrome and colour printing options available?How long does it take to produce a print-out?Can the size of the print-out be controlled?

v) What are the resource commitments for this element of the system?

Being a relatively new technology, the costs of GIS are high. Unlessconsidered carefully this element of the system can easily put the cost ofLCA way beyond the available budget.

What are the costs for the digitised map data(purchase/license/updates/support/cost per print)?What are the additional hardware, operating system and softwarerequirements?What additional peripheral equipment is required (eg digitiser, colour printer)?What ace their costs for purchase, maintenance and support?What are the training requirements and costs?

Other requirements

Other general system requirements are included in this final part of thechecklist.

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i) Is the overall system easy to use

Users of LCA systems are unlikely to be trained computer specialists norexperienced statisticians. LCA systems must be designed to be easy to usewith little training.

What is the overall training requirement for the system?Does the system have any interactive training facilities?Can menu structures, screen designs and other interface features be customisedto meet the local requirement?Does the system have an on-line help facility?Does the system support both new users and advanced users?How easy is it to navigate through the elements of the system?Can each of the analysis facilities support a library of regularly used operations?Are the system response times adequate for interactive use?

ii) Is the system appropriate for sub-divisional use?

LCA systems tend to be used at the sub-divisional (or equivalent) level,where there is the knowledge of local crime problems and control of theresources to respond to the problems.

Is the system sufficiently robust to operate at sub-divisional level?Is the system sufficiently cheap to be implemented at sub-divisional level?Is the system sufficiently supported to be implemented at sub-divisional level?Can the system provide a high level of availability for all routine operations?

iii) Does the system meet relevant standards?

Any investment in LCA systems must be seen as a contribution to theoverall development of computer support for the police.

Does the system comply with:- the national IS/IT strategy- the force IT strategy?- crime data standards (eg ACPO CCCIS)?- general system standards (eg CCTA CC88)?- the Data Protection Act?

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iv) Does the system provide adequate security functions?

Forces must assess the security requirements for their implementation 0 LCASystems.

Can password security be set up?Can the system limit functionality according to user type (analyst, systemmanager, data inputter, read-only enquiries)?

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In the preparation of this report a number of police forces and commercialorganisations offering LCA systems were contacted. Details of these areprovided below. The list is not designed to be comprehensive, nor is it likelyto remain up-to-date:-

System and Contact Name Address and Telephone Number

Active Software - Paul Smith Active Software, Datum House, RoentgenRoad, Basingstoke. Tel (01256) 56629

Claris - Phil Atkinson Claris International, 1 Roundwood Avenue,Stockley Park, Uxbridge UB11 1BG.Tel (0181) 756 0101

CPAS - Vic Way Sanderson Insight Ltd, Bedford Road,Wootton, Bedford, MK43 9JB.Tel (01234) 768557

Crime - Superintendent Gil Oxley Police Station, West Midlands Police,Homer Rd, Solihull, West Midlands B913QL. Tel (0121) 712 6000

EPIC - David McCaddon ICL Government & Major Companies Law& Order Branch, ICL (UK) Ltd, ArndaleHouse, Arndale Centre, Manchester M43AR.Tel (0161) 8339 111

Famous - John Griffiths Griffiths Associates Ltd, Penylan House,Pencoed, Mid Glamorgan CF35 6LT Tel(01656) 862653

FastCad - Joe Stelzer FastCad GIS ltd, 26 Greenhill Crescent,Watford Business Park, Watford WD1 8XG.Tel (01923) 240272

Greater Manchester Police - Greater Manchester Police, P0 Box 22,(system developed in house - Chester House, Boyer St,Paradox based) Manchester M16 ORE.

Tel (0161) 872 5050

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Appendix C LCA contact list

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System and Contact Name Address and Telephone Number

JOCA - Arthur Jordan Clapham Police Station, Metropolitan(system developed in house) Police, 51 Union Grove, SW8 2QU.

Tel (0171) 326 1212

Enfield Police Station DIIU, Metropolitan Police, Enfield Police(System developed in house - Station, 41 Baker Street, Enfield, MiddlesexMapInfo based) EN1 3EU. Tel 0181-366-1212

Memex Memex Information Systems ltd, 16 AlbionWay, East Kilbride, Scotland G75 0YN.Tel (013552) 33804

Merseyside Police - Inspector Wavertree Road Police Station, Merseyside Mike Barron (System developed Police, Liverpool L71RJ. Tel (0151) 709 6010in house - ArcInfo/Paradox based)

Pafec Pafec Ltd, Strelley Hall, Nottingham, NG86PE. Tel (0115) 9357055

Plan Chest - David Hunt Graphical Data Capture Ltd, 262 RegentsPark Road, London N3.Tel (0181) 3494095

Proquest - Dr Bruce Hattersley Lenken Europe, Tower Factory, Well Street,Finedon, Northants NN9 5JP.Tel (01933) 682020

STAC - Peg Dabdoub Illinois Criminal Justice Authority, 120South Riverside Plaza, Chicago, Illinois60606-3997.

Trilogy - John Upson Trilogy Computers, Sovereign Court, MiltonKeynes. Tel (01908) 690509

Watson - Richard Mills Harlequin Ltd, Barrington Hall, Barrington,Cambridge CB2 5RG. Tel 01223 873800

West Yorkshire Police - Information Technology Department, WestGraham Dawson Yorkshire Police, Bayheath House,

Wakefield. Tel 01924 293400

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55. Witness Intimidation: Strategies for prevention.Warwick Maynard 1994.

56. Preventing Vandalism: What Works? Mary Barker and Cressida Bridgeman. 1994.

57. Thinking About Crime Prevention Performance Indicators. Nick Tilley. 1995.

58. Biting Back: Tackling Repeat Burglary and Car Crime. DavidAnderson, Sylvia Chenery and Ken Pease. 1995.

59. Combating Burglary: An Evaluation of Three Strategies.Janet Stockdale and Peter Gresham. 1995.

60. Policing and Neighbourhood Watch: Strategic Issues. Gloria Laycock and Nick Tilley. 1995.

61. Investigating, seizing and confiscating the proceeds of crime.Michael Levi and Lisa Osofsky. 1995.

62. Performance Indicators for Local Anti-Drugs Strategies – APreliminary Analysis. Mike Chatterton, Christine Godfrey, GwendyGibson, Mark Gilman, Matthew Sutton and Alan Wright. 1995.

63. Preventing School Bullying. John Pitts and Philip Smith. 1995.

64. Intelligence, Surveillance and Informants: IntegratedApproaches. Mike Maguire and Timothy John. 1995.

CRIME DETECTION AND PREVENTION SERIES PAPERS

Recent Police Research Group Crime Detectionand Prevention Series Papers:

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Home OfficePolice Department

Paper 65: Local C

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local crime analysis - college of policinglibrary.college.police.uk/docs/hopolicers/fcdps65.pdf ·...

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