M_07_ch9su_MEASUREMENT_SCALING_RELIABILI.pptx

1. CH. 9
MEASUREMENT: SCALING,
RELIABILITY, VALIDITY
Presented by
Helmi Ali Akbar

2. CH. 9
MEASUREMENT: SCALING,
RELIABILITY, VALIDITY

3. Scaling
 Scaling is a procedure for the assignment
of numbers (or other symbols) to a
property of objects in order to import
some of the characteristics of numbers to
properties in question

4. Methods of Scaling
 Rating scales
 Have several response categories and are
used to elicit responses with regard to the
object, event, or person studied.
 Ranking scales
 Make comparisons between or among
objects, events, persons and elicit the
preferred choices and ranking among
them.

5. Rating Scales
 Dichotomous scale
 Is used to elicit a Yes or No answer.
 Nominal scale

6. Dichotomous Scale
Do you own a car?
Yes
No

7. Rating Scales (Cont’d)
 Category scale
 Uses multiple items to elicit a single
response.
 Nominal scale

8. Category Scale
Where in northern California do you reside?
North Bay
South Bay
East Bay
Peninsula
Other (specify:_____________)

9. Rating Scales (Cont’d)
 Likert scale
 Is designed to examine how strongly
subjects agree or disagree with statements
on a 5-point scale.
 Interval scale

10. Likert Scale
My work is very interesting
Strongly disagree
Disagree
Neither agree nor disagree
Agree
Strongly agree

11. Rating Scales (Cont’d)
 Semantic differential scale
 Several bipolar attributes are identified at
the extremes of the scale, and respondents
are asked to indicate their attitudes.
 Interval scale

12. Semantic Differential

13. Rating Scales (Cont’d)
 Numerical scale
 Similar to the semantic differential scale,
with the difference that numbers on a 5-
point or 7-point scale are provided, with
bipolar adjectives at both ends.
 Interval scale

14. Numerical Scale
How pleased are you with your new real estate
agent?
Extremely 7 6 5 4 3 2 1 Extremely
Pleased Displeased

15. Rating Scales (Cont’d)
 Itemized rating scale
 A 5-point or 7-point scale with anchors, as
needed, is provided for each item and the
respondent states the appropriate number
on the side of each item, or circles the
relevant number against each item.
 Interval scale

16. 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

17. Rating Scales (Cont’d)
 Fixed or constant sum scale
 The respondents are here asked to
distribute a given number of points across
various items.
 Ordinal scale

18. Fixed or Constant-Sum Scales

19. Rating Scales (Cont’d)
 Stapel scale
 This scale simultaneously measure both the
direction and intensity of the attitude
toward the items under study.
 Interval data

20. Stapel Scales

21. Rating Scales (Cont’d)
 Graphic rating scale
 A graphical representation helps the
respondents to indicate on this scale their
answers to particular question by placing a
mark at the appropriate point on the line.
 Ordinal scale

22. Graphic Rating Scales

23. Ranking Scales
 Paired Comparison
 Used when, among a small number of
objects, respondents are asked to choose
between two objects at a time.

24. Paired-Comparison Scale

25. Ranking Scales (Cont’d)
 Forced Choice
 Enable respondents to rank objects relative
to one another, among the alternatives
provided.

26. Forced Choice

27. Ranking Scales (Cont’d)
 Comparative Scale
 Provides a benchmark or a point of reference
to assess attitudes toward the current object,
event, or situation under study.

28. Comparative Scale

29. Goodness of Measures
 Reliability
 Indicates the extent to which it is without
bias (error free) and hence ensures
consistent measurement across time and
across the various items in the instrument.

30. Reliability
 Stability of measures:
 Test-retest reliability
 Parallel-form reliability
 Correlation
 Internal consistency of measures:
 Interitem consistency reliability
 Cronbach’s alpha
 Split-half reliability
 Correlation

31. Goodness of Measures
(Cont’d)
 Validity
 Ensures the ability of a scale to measure the
intended concept.
 Content validity
 Criterion related validity
 Construct validity

32. Validity
 Content validity
 Ensures that the measure includes an
adequate and representative set of items
that tap the concept.
 A panel of judges

33. Validity (Cont’d)
 Criterion related validity
 Is established when the measure
differentiates individuals on a criterion it is
expected to predict
 Concurrent validity: established when the
scale differentiates individuals who are known
to be different
 Predictive validity: indicates the ability of
measuring instrument to differentiate among
individuals with reference to future criterion
 Correlation

34. Validity (Cont’d)
 Construct validity
 Testifies to how well the results obtained from the
use of the measure fit the theories around which the
test is designed.
 Convergent validity: established when the scores
obtained with two different instrument measuring the
same 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 indeed
empirically found to be so
 Correlation, factor analysis, convergent-discriminant
techniques, multitrait-multimethod analysis

35. Understanding Validity and Reliability