mearurement measurement scales

7/29/2019 Mearurement Measurement Scales

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Measurement and

Measurement/Attitudescales


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Measurement and Scaling

Measurement means assigning numbers orother symbols to characteristics of objects

according to certain pre-specified rules.

One-to-one correspondence between the numbersand the characteristics being measured.

The rules for assigning numbers should be

standardized and applied uniformly.

Rules must not change over objects or time.


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Measurement and Scaling

Scaling involves creating a continuum uponwhich measured objects are located.

Consider an attitude scale from 1 to 100. Eachrespondent is assigned a number from 1 to 100, with 1 =

Extremely Unfavorable, and 100 = Extremely Favorable.

Measurement is the actual assignment of a number from

1 to 100 to each respondent. Scaling is the process ofplacing the respondents on a continuum with respect to

their attitude toward department stores.


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Primary Scales of Measurement

7 38

Scale

Nominal NumbersAssignedto Runners

Ordinal Rank Orderof Winners

Interval PerformanceRating on a0 to 10 Scale

Ratio Time to

Finish, inSeconds

Thirdplace

Secondplace

Firstplace

Finish

Finish

8.2 9.1 9.6

15.2 14.1 13.4


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DEFINITION OF ATTITUDE

A learned predisposition to respond in a

consistently favourable or unfavourableway to some aspect of the individuals

environment


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COMPONENTS OF AN ATTITUDE

An attitude is an underlying construct

As an operational variable, it is an

evaluated belief that predisposes the

holder to behave in one way or another.

Three components

a belief component

the affective component

the behavioural component


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THREE COMPONENTS

Three components a belief component I believe that.

the affective component emotional-evaluative component

the behavioural component what theperson does on the basis of the two

previous components


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Attitude Measurement

Most widely used approach to attitude measurement isthe application of standardized attitude questionnaires orscales

An attitude scale usually consists of sets of statementsor words relating to an attitude item.

Individual items in an attitude scale are usually not of

interest in themselves; the interest is normally located inthe total score or mean of sets of items grouped on thebasis of factor analysis or Cronbach alpha reliability,i.e.we know all the items are measuring the same thing


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ATTITUDE SCALES

An attitude scale usually uses sets of

statements or words relating to an attitude

item.

They are usually concerned with

measuring the degree of positive or

negative feeling (evaluation), that is

degree of favourability, towards theperson, object or event.

The best-known rating scale techniques

are described below.


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TYPES OF ATTITUDE SCALE

Differential Scales (Thurstone Type)

The Likert Scale

The Semantic Differential (Osgood)

Kelly's Repertory Grid Technique


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DIFFERENTIAL SCALES (THURSTONETYPE)

Initial selection of a large number of evaluative-tinged

statements about a particular object or topic

Judges assess the degree to which each statement

expresses a positive or negative attitude towards the object A calculation is made of the median score for each item

using scale values

Scale values indicate the degree to which it represents a

favourable or unfavourable attitude

Selection of items made on basis of covering scale value

range with items on which there is small range of judgement

variation


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DIFFERENTIAL SCALES (THURSTONETYPE)

Scale Value Statement0.5 I believe Savemor provides the best value of any

supermarket chain in the country

2.4 I believe Savemor has the consumers needs atheart

5.2 I believe Savemor is as good as any other supermarket.8.7 I believe Savemor sacrifices quality for cheapness.10.3 I believe Savemor should be boycotted because of its policy

towards unionization.


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THE LIKERT SCALE

Subjects are asked to what extent they agree or disagree with eachstatement

Items are placed in the scale at random and may be positive ornegative towards the topic

* Reverse scoring on this item - all items marked favourably towardstrade unions should be scored in the same direction.

Items worded in a reverse direction are placed at random to stoppeople filling in the scale carelessly by going down in one column.

SA A ? D SD1* Trade unions hold back progress. 1 2 3 4 5

2 I regard my union subscription as 1 2 3 4 5a goodinvestment.

3 Every employee should be 1 2 3 4 5compelled by law to join their union.


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ADVANTAGE OF LIKERT

METHOD

1. Greater ease of preparation than the Thurstonetechnique.

2. The method is based entirely on empirical dataregarding subject's responses rather thansubjective opinions of judges.

3. This method produces more homogeneous scalesand increases the probability that a unitary attitude

is being measured, increasing validity (constructand concurrent) and reliability.

4. As a result most attitude researchers have reliedon easier to construct Likert scaling procedure to

measure attitudes.


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DISADVANTAGE OF LIKERT SCALES

The Likert-type scale is only an ordinal scale, i.e. it makes possible theranking of individuals in terms of the favourableness of their attitude towarda given object, but it does not provide a basis for saying how much morefavourableone is than another. Whether this constitutes a disadvantage ofthe Likert scale in comparison with the Thurstone scale depends on one's

judgement of whether Thurstone scales really meet the criteria for interval

scales! Most attitude investigators do assume Likert scales provideinterval data

The total score of an individual has little clear meaning, since manypatterns of response to the various items may produce the same score.Thurstone-type scales are also subject to this criticism, but it applies even

more strongly to the Likert scales, since they provide a greater number ofresponse possibilities and combinations.

The midpoint suffers from problems of definition. Should we name it dontknow or no opinion or neutral etc. All these have slightly differentmeanings.


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THE SEMANTIC DIFFERENTIAL

The Semantic Differential requires a list ofbipolar scales with usually seven rating points

lying between each end of the scale. They are

bipolar scales since each end is denoted by the

antonym of the other end.

Thus it is common to use adjectives like happy-

sad to characterise the opposite poles.Descriptive phrases too such as staff are

courteous - staff are not courteous are used


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THE SEMANTIC DIFFERENTIAL

Bi-polar adjective or adjective phrases are

chosen as items on the basis of relevance to

the concept being rated

Concept to be Rated e.g. Supervisor A+3 +2 +1 0 -1 -2 -3

Good X Bad

Modern Old fashioned

Reliable X Unreliable

Responsible X Irresponsible

Uninterested in

employees

welfare

X Interested in

employees welfare


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COMPARISON OF TWO BRANDS

Brand A versus Brand B (or ideal Brand A)

High price 1 2 3 4 5 6 7 Low price

High calories 1 2 3 4 5 6 7 Low calories

High fat 1 2 3 4 5 6 7 Low fat content

content

Highly sweet 1 2 3 4 5 6 7 Unsweetened

etc

Key: Rating of Brand A

Rating of Brand B (or ideal Brand A)


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COMPARISON OF TWO BRANDS

Brand A Brand B (or ideal)

Price 2 5

Calories 6 7

Fat 5 7

Sweetness 3 5

Total 16 24


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SEMANTIC DIFFERENTIAL PROFILE

ORGANISATION A

+3 +2 +1 0 -1 -2 -3

Good Bad

Modern Oldfashioned

Healthy Unhealthy

Energetic Lethargic

Responsible Irresponsible

Important Unimportant


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KELLY'S REPERTORY GRIDTECHNIQUE

Devised as a means of mapping an

individual's personal constructs

a way in which two things are alike and inthe same way different from a third

Respondents consider three objects,

persons, etc., to determine in which way

two are alike( marked A) but also different

from a third (marked D)


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KELLY'S REPERTORY GRIDTECHNIQUE

EXAMPLE: Repertory Grid for Brands of Beer

Constructs Brand A Brand B Brand C Brand D Brand E

Strong A A DMan's drink A A DReasonably priced A A D

Real ale A D AGood taste A A DArtificial taste A D AGood colour A A D


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THE RELIABILITY AND VALIDITYOF ATTITUDE SCALES

The reliability of attitude scales is usually assessed via

the test-retest method

Internal reliability is also sought. Acceptable levels of

Cronbach alpha for attitudes scales is 0.7 and above

Alpha coefficient range Strength of association


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VALIDITY

The validity of attitude scales is often checked byconcurrent validity using known criterion groups

Predictive validity is also possible by selecting some

criterion in the future such as product purchasingbehaviour

Construct validity is measured by correlating with otherknown measures of the same construct

Content validity is usually easily detectable by inspectionof item content


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RELIABILITY AND VALIDITY

These important concepts relate to any measure/instrument

1. Validity of a measure: The degree to which a measureactually measures what we think it measures.

2. Reliability of a measure: The consistency of a measure overtime or under similar situations.

In social, or business research we cannot expect any measureto be perfectly valid or perfectly reliable. The best we can do

is to design our measures to be as valid and reliable as theycan be and where feasible run some statistical tests toevaluate their levels of reliability and validity.

.


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DETERMINING RELIABILITY

1. Test-retest reliability. The degree to which themeasure returns the same value from the same

respondents on a second occasion. Temporal

reliability or stability over time

2. Parallel-form reliability. When two equivalent (butdifferent) forms of a measure are developed (e.g.

two equivalent forms of a single personality scale

are developed), it is the degree to which the same

value is returned from the same respondents for

the two different equivalent forms.


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DETERMINING RELIABILITY

3. Split-Half or Inter-Item Method A measure of reliability reflecting the degree to which

one half of the items is the same as that for the otherhalf of the items (like a test-retest, but can beperformed on a single occasion).

Problem how do we determinewhich items should be in each half?

Often worked on the odd-even items on a scale/test.

4. Internal Consistency Method (Cronbachs Alpha) A measure of reliability that is equivalent to the

mathematical average of all possible split halfcombinations.


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CRONBACH ALPHA INTERNAL

RELIABILITY ANALYSIS Select Analyze, choose Scaleand click on Reliability

Analysisto open the Reliability Analysis dialoguebox.

Transfer all the scale or subtest items to the Itemsbox.

Ensure Alphais chosen in the Modelbox Click on Statisticsto open the Reliability Analysis

Statistics dialoguebox.

In the Descriptivesfor area, select Item, Scaleand

Scaleif item deleted. In the Inter-itemarea choose Correlations

Select Continuethen OKto produce the output


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Cronbach Alpha Analysis Printout

Item-total Statistics

Scale Scale Corrected

Mean Variance Item- Alpha

if Item if Item Total if Item

Deleted Deleted Correlation Deleted

Q1 34.1939 32.3228 .6455 .8462

Q2 34.2755 33.1914 .5686 .8525

Q3 34.2653 31.4959 .7414 .8383Q4 34.1531 32.6258 .6756 .8445

Q5 34.3878 32.1368 .7492 .8392

Q6 34.2347 32.1196 .7459 .8393

Q7 34.2245 31.9903 .6860 .8429

Q8 34.1837 31.7391 .7225 .8400

Q9 34.1735 31.0727 .7082 .8402

Q10 35.5612 40.7436 -.1369 .9175

Reliability Coefficients

N of Cases = 98.0 N of Items = 10

Alpha = .8647

This item

stands out

This will be

the alpha ifwe leave this

item out


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CRONBACH ALPHA INTERNAL

RELIABILITY ANALYSIS The two columns to focus on are the last two. The Corrected Item-Total Correlation reveals those items

that have low correlations with the test or scale as awhole. Here item 10 stands out as the correlation is notonly lower than the rest but it is also negative.

The last column shows the overall scale alpha or internalreliability if that item is removed. If item 10 is removedthe overall scale alpha rises to .9175, much higher thanthe current alpha and indicative of a scale with very highinternal consistency, i.e. all items measuring the same

concept. The overall alpha is .8647, printed below the bottom sub-

table. This is quite acceptable but by eliminating item 10we do have the option of an even higher value.


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GENERAL CRITICISMS OF ATTITUDE SCALES

Attitude scales can be easily faked self report measures are limited by what a

subject is willing to reveal about themselves

and depends on such factors as

willingness to cooperate,

social expectancy,

feelings of personal adequacy,

feelings of freedom from threat,

dishonesty, carelessness, ulterior

motivation,

interpretation of verbal stimuli.


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GENERAL CRITICISMS OFATTITUDE SCALES

Response sets such as acquiescence (thetendency to agree with items irrespectiveof their content) and social desirability (the

tendency to agree to statements whichsocial consensus would support) fog thedata derived from attitude scales.

The best way of eliminating acquiescence

and social desirability is to order randomlypositive and negative items to prevent asubject ticking madly away down the same

column

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