Research Methodology Nominal Data, Ordinal data, Interval data, Ratio data Scaling techniques Likert Scale

1. Measuremen
t and Scaling
JITHIN K THOMAS
Berchmans Institute of Management Studies

2. Measurement and Scaling
• Measurement is the assignment of numbers
to objects to represent amounts and degrees
of a property possessed by all of the objects.
• A number system
– Order
– Distance
– Origin

3. Nominal Data
• Most elementary form of measurement
• Which partitions a set into categories that are
mutually exclusive and collectively exhaustive.
• Each category is assigned a number.
• No order, no distance and no arithmetic
relationship.
• Ex: Sex
• Mode is the only measure of central tendency
• Chi square test, Fishers exact tests

4. Ordinal Data
• Ordinal scale places events in order
• But no distance and origin
• Transitivity postulate
• Implies a grater than or less than relationship
• Median is the popular measure if central
tendency
• Ex: Rank
• Percentile or quartile is used for measuring
dispersion
• Non parametric tests

5. Interval Data
• Interval scale has order and distance
• Intervals between two points are adjusted in
terms of some rule that has been established
for purpose of making the units equal.
• Ex: temperature
• It has assumed zero but no absolute zero
• Mean, Standard deviation
• T test and F test

6. Ratio Data
• Order, distance and unique origin
• Ex: Height, weight
• Geometric mean, harmonic mean
• Variance and co-efficient of variance
• All parametric tests

7. Source of Measurement Error
• Respondent
– Fatigue, boredom, shyness, ignorance
• Situation
– Strain
• Measurer
– Rewording, reordering, incorrect coding, tabulation
• Instrument
– Complex wording, poor printing, defective measuring
instrument, poor sampling

8. Goodness of Measures
• Validity
– internal validity and external validity
a) Content Validity
b) Criterion related validity
c) Construct Validity

9. Goodness of Measures
• Reliability
– Stability
– Consistency
• Practicality
– Economy
– Convenience
– Interpretability

10. Scaling
• Procedure for assigning of numbers to a
property of objects in order to impart some of
the characteristics of numbers to the
properties in question

11. Scale Classification
• Study objective
• Response form
• Degree of subjectivity
• Number of dimensions
• Scale properties
• Scale construction techniques
– Arbitrary
– Consensus
– Item analysis
– Factor scale

12. Scaling Techniques
• Rating scale
– Graphic Rating scale
– Itemizes rating scale
• Halo effect
• Generosity error
• Contrast error

13. Scaling Techniques
• Ranking Scale
– Objects are ranked after comparing one against
another or more
a) Paired comparison scale
– Compares two items at a time
a) Rank order scale
– Respondents are given a set of items
simultaneously and asked to rank them according
some criteria

14. Scale Construction Techniques
• Arbitrary Scale
– Constructed based on the researchers subjective
evaluation of statements that he believe are
unambiguous and appropriate to a given topic.

15. Thurston Differential Scale
• Based on consensus approach where the items to be
included in the scale are decided upon by a panel of
judges.
– Large no.of (20 or more) are statements collected
– Eliminates ambiguous and duplicate statements
– Judges around 50 to 80 independently evaluate them
– Sort them into piles of 11/9/7
– Score the piles from 1 to 11/9/7
– Disregard items which have high scatter value
– Select the reminder, around 20 or so
– Items included in a questionnaire randomly arranged
– Respondents tick all the items which he/she agrees.

16. Thurston Differential Scale
• Advantages
– Measure the attitude of people towards issues like
casteism, war, government etc
– Works best when only a single attitude is to be
measured
– It is very simple to attempt.
• Disadvantage
– Difficult to construct and expensive.

17. Likert Scale
• Respondent is asked to indicate the degree of
agreement or disagreement with each
statement in the instrument.
– Collect large no.of statements
– Clear and unambiguous
– Equal favorable and unfavorable statements
– Administered to sample of subjects
Strongly
agree
Agree Undecided Disagree Strongly
disagree
Standard of living of a
person can be increased
by borrowing

18. Likert Scale
• Each response is given a numerical value
• Total score is calculated
• Discriminatory power is calculated for each
item
• Statements which correlate with test score are
retained.

19. Advantages of Likert Scale
• Simpler and easier to construct
• Same time and cost
• Eliminates ambiguity
• More complete evaluation
• More comprehensive
• Can be used in response centered and
stimulus centered studies

20. Disadvantages of Likert Scale
• Gives total scores but not the pattern of
response
• No consensus on optimal no.of categories
• No way of ascertaining the distance between
• How much more favorable or unfavorable
• Respondents answer ‘what should be’ than on
‘what actually is’

21. Guttman Scalogram
• It’s a cumulative scale
• Respondent indicate agreement or
disagreement
• Individual total score is calculated by counting
the no.of items answered favorably.

22. Guttman Scalogram
• Advantages
– Superioir to Likert and Thurston
– Is unidimensional scale – clear meaning
• Disadvantages
– Analytical complexity
– Difficult to find items which have a perfect
cumulative pattern.

23. Sematic Differential Scale
• Useful in bringing out latent feelings of
respondents.
• It’s a bipolar scale with seven rating points.

24. Multidimensional Scaling
• Taking two or three dimensional pictures of a
many dimensional term space