msc projects information searching peter hancox computer …rzb/information_searching.pdf ·...

MSc Projects – Information Searching

MSc ProjectsInformation Searching

Peter HancoxComputer Science


Why should you be searching?

– saving you time by finding ways to solve problems, produce better designs, discover problem domains, benchmark your work;

Information searching/retrieval is about:

Introduction to information retrieval 1

produce better designs, discover problem domains, benchmark your work;

– learning from other people’s work;– developing problem-solving skills;– keeping your examiners happy.


IR is more than Google

Most people’s way of finding information is to use Google.

Google is great for some things - mainly finding

What were the surnames of my grandfathers?

Is the Earth flat? See:http://www.alaska.net/~clund/e_djublonskopf/Flatearthsociety.htm


Google is great for some things - mainly finding undisputed facts.

Google relies on indexing WWW pages - so it is as:– complete as the WWW;– accurate as the WWW.


The Computer Science literature

3%7%

Conference papers

Journal articles

Technical reports


39%

26%

5%

3%

17%Technical reports

Theses

Books

Other material (egprograms)

WWW pages


How to know you’re getting quality

Journal papers- the best are “peer-reviewed”

How do you, a novice, know you’re reading high quality scientific/technical literature?


Journal papers- the best are “peer-reviewed”Conference papers- the best are “peer-reviewed”Books- the best are published by the best publishers, e.g. Oxford, Cambridge, MIT, ….Technical reports- the best probably come from the best universities and companies …But how do you know which are the best?


How to know you’re getting quality

The answer is very simple:

Use specialised information retrieval databases that have


Use specialised information retrieval databases that have– excellentcoverage;– excellent currency.


Some IR theory and practice - 1

There are three kinds of search:

– finding simple facts- use Google (with care)– current awareness- keeping yourself up-to-date


– current awareness- keeping yourself up-to-date– retrospective searching- finding some (or all) the

literature on a topic

This lecture is mainly about retrospective searching.



A document set can be divided into relevant and irrelevant documents:





Precision =


Precision = no. of relevant documentstotal no. of docs retrieved

100/160 = 62.5%




Recall =


Recall = no. of relevant documentstotal no. of relevant docs

100/200 = 50%



The paradox of searching? It seems impossible to get 100% precision and 100% recall.


100% precision and 100% recall.



Bradford’s law of scattering:

Colloquially:To find all relevant scientific literature on a topic, you


To find all relevant scientific literature on a topic, you have to look in all the literature; to find ~90% of the literature, you only have to look in 10% of the literature.

More formally:the returns of extending a search for references in science journals diminishes exponentially.



Bradford’s law of scattering:

Means that we can concentrate searching on a fairly small subset of the literature and get most results.


subset of the literature and get most results.

Specialised information retrieval databases are designed to retrieve large amounts of literature from the optimum number of journals. Google isn’t designed to do this.


Choosing databases - books

Don’t use Amazon - it only has books currently on sale that it can source.

Use a copyright deposit library:

Databases - books 13

Use a copyright deposit library:British LibraryLibrary of CongressCambridge UL


Choosing databasesjournals and conference papers

The best keyword-based Computer Science services are:

Inspec

Databases - journals and conference papers 14

Inspechttp://www.engineeringvillage2.org

ACM Guide to Computing Literaturehttp://portal.acm.org/guide.cfm



Interdisciplinary services with substantial Computing coverage:


Medlinehttp://gateway.ovid.com/autologin.html

Compendex/Engineering Indexhttp://www.engineeringvillage2.org



Single publisher services - perhaps with full text access:

IEEE Xplore


IEEE Xplorehttp://ieeexplore.ieee.org/


Inspec - coverage and currency

Includes:– 3,500 journals – many of them computing science

and applications journals– conference papers – 1,500 conferences added each

year

Searching Inspec 17

– conference papers – 1,500 conferences added each year

– seems to include reports, theses, etc, but how satisfactory is the coverage?

Journals seem to be completely indexed within ~6 months of publication.


Inspec - indexing

How are the entries indexed?– Classification scheme– Controlled language

Searching Inspec 18

– Controlled language– Keywords

• taken from title• taken from abstract• written by the indexer


Inspec - indexing

Searching Inspec 19

ti: coherenceti: inferenceti: representation


Inspec - indexing

Searching Inspec 20


Inspec - searching

Demonstration based on handout.

Searching Inspec 21


Science Citation Index Subject coverage

The scope is so wide as to be multidisciplinary.

It indexes:

Searching Science Citation Index 22

It indexes:– journals - almost 5,300 science journals including at

least 200 computing journals and probably more.It doesn’t directly index:– conferences – books– reports – theses

Inspec indexes 3,500 mainly relevant journals


Science Citation IndexComprehensiveness/coverage

Covers many of the principal journals in computing– has a wide computer science coverage, choosing the


– has a wide computer science coverage, choosing the most widely respected journals rather than (e.g.) an engineering bias.


Science Citation IndexSubject overlap

SCIoverlaps with several other indexing services.– Compendexhas many of the same core journals - but

also has conferences.


also has conferences.– Inspechas many of the same core journals and lots of

other journals - and also has conferences.


Science Citation IndexRecord content

How much information do the entries contain?– Basic bibliographic information– Abstract


– Abstract– Institution - e.g. University of Birmingham– Language of original article


Science Citation Index Indexing

How are the entries indexed?– Keywords

• taken from title


• taken from title• taken from abstract• written by the indexer

– Citations


SCI - searching

Demonstration based on handout.



So what does SCI retrieve?

If you use it as keyword-based indexOnly journals/serials


If you search for citationsAnything that authors cite …– journal & conference papers, books, theses, technical

reports– letters, WWW pages, newspapers, conversations …


Searching SCI for citations

Points to think aboutDoes the use of citations improve recall and/or precision?


precision?

What criteria are used to include cited items? – Are items cited because they are relevant?– Because the author wrote them? – To criticize an alternative approach? – To impress readers with the author’s erudition?


The End

30

The End

msc projects information searching peter hancox computer …rzb/information_searching.pdf ·...

Documents