Pertemuan 8 (Scaling)

7/28/2019 Pertemuan 8 (Scaling)

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MEASUREMENT: SCALING,

RELIABILITY, VALIDITY


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Scaling

Scaling is a procedure for the assignmentof numbers (or other symbols) to aproperty of objects in order to importsome of the characteristics of numbers toproperties in question


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Methods of Scaling

Rating scales

Have several response categories and are

used to elicit responses with regard to theobject, event, or person studied.

Ranking scales

Make comparisons between or among

objects, events, persons and elicit thepreferred choices and ranking amongthem.


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Rating Scales

Dichotomous scale

Is used to elicit a Yes or No answer.

Nominal scale


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Dichotomous Scale

Do you own a car?

Yes

No


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Rating Scales (Contd)

Category scale

Uses multiple items to elicit a single

response. Nominal scale


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Category Scale

Where in northern California do you reside?

North Bay

South Bay

East Bay

Peninsula

Other (specify:_____________)


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Likert scale

Is designed to examine how strongly

subjects agree or disagree with statementson a 5-point scale.

Interval scale


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Likert Scale

My work is very interesting

Strongly disagree

Disagree

Neither agree nor disagree

Agree

Strongly agree


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Semantic differential scale

Several bipolar attributes are identified at

the extremes of the scale, and respondentsare asked to indicate their attitudes.

Interval scale


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Semantic Differential


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Numerical scale

Similar to the semantic differential scale,

with the difference that numbers on a 5-point or 7-point scale are provided, withbipolar adjectives at both ends.

Interval scale


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Numerical Scale

How pleased are you with your new real estateagent?

Extremely 7 6 5 4 3 2 1 Extremely

Pleased Displeased


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Itemized rating scale

A 5-point or 7-point scale with anchors, as

needed, is provided for each item and therespondent states the appropriate numberon the side of each item, or circles therelevant number against each item.

Interval scale


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Itemized Rating Scale

1 2 3 4 5

Very Unlikely Unlikely Neither Unlikely Likely Very Likely

Nor Likely

1. I will be changing my job within the next 12 months


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Fixed or constant sum scale

The respondents are here asked to

distribute a given number of points acrossvarious items.

Ordinal scale


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Fixed or Constant-Sum Scales


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Stapel scale

This scale simultaneously measure both the

direction and intensity of the attitudetoward the items under study.

Interval data


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Stapel Scales


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Graphic rating scale

A graphical representation helps the

respondents to indicate on this scale theiranswers to particular question by placing amark at the appropriate point on the line.

Ordinal scale


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Graphic Rating Scales


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Ranking Scales

Paired Comparison

Used when, among a small number ofobjects, respondents are asked to choose

between two objects at a time.


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Paired-Comparison Scale


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Ranking Scales (Contd)

Forced Choice

Enable respondents to rank objects relativeto one another, among the alternatives

provided.


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Forced Choice


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Ranking Scales (Contd)

Comparative Scale

Provides a benchmark or a point of referenceto assess attitudes toward the current object,

event, or situation under study.


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Comparative Scale


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Goodness of Measures

Reliability

Indicates the extent to which it is withoutbias (error free) and hence ensures

consistent measurement across time andacross the various items in the instrument.


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Reliability

Stability of measures:

Test-retest reliability

Parallel-form reliability

Correlation

Internal consistency of measures:

Interitem consistency reliability

Cronbachs alpha

Split-half reliability

Correlation


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Goodness of Measures(Contd)

Validity

Ensures the ability of a scale to measure theintended concept.

Content validity

Criterion related validity

Construct validity


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Validity

Content validity

Ensures that the measure includes anadequate and representative set of items

that tap the concept. A panel of judges


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Validity (Contd)

Criterion related validity

Is established when the measuredifferentiates individuals on a criterion it is

expected to predict Concurrent validity: established when the

scale differentiates individuals who are knownto be different

Predictive validity: indicates the ability ofmeasuring instrument to differentiate amongindividuals with reference to future criterion

Correlation


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Validity (Contd)

Construct validity

Testifies to how well the results obtained from theuse of the measure fit the theories around which thetest is designed.

Convergent validity: established when the scoresobtained with two different instrument measuring thesame concept are highly correlated

Discriminant validity: established when, based on

theory, two variables are predicted to be uncorrelated,and the scores obtained by measuring them are indeedempirically found to be so

Correlation, factor analysis, convergent-discriminanttechniques, multitrait-multimethod analysis


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Understanding Validity and Reliability

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Pertemuan 8 (Scaling)