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Chapter 7
Measurement of Variables:
Scales, Reliability and Validity
Scales
A scale is a mechanism or tool by which unit of
analysis are distinguished on the variables of
the interest of the study.
Every scale should have at least two important qualities
• Exhaustiveness
You should be able to classify every observation (or
response) in terms of the attributes composing the
variable (scale).
Assist. Prof. Dr. Özge Özgen
Research Methodology
• Mutually Exclusiveness
You should be able to classify every observation (or
response) in terms of one and only one attribute
composing the variable (scale).
Examples (exhaustiveness and mutually exclusiveness)
Indicators for Dimension 2 (Figure 8.1)
Q: What is your education level?
1.
2.
3.
Not Exhaustive
Exhaustive
1)
2)
3)
4)
1) No education
2) Elementary school
3) Junior high school
4) High school
5) University
6) Above university
Elementary school
Junior high school
High school
University
Some Possible Questions for each indicator (Figure 8.1)
1.
How frequently do you think of work while at home?
(1) Often
(2) Sometimes
Mutually Exclusive
1) Full-time
2) Part-time
3) Both
(3) Never
2.
Do you have any hobbies? If so, how many hours do you
spend a week for your hobbies?
3.
How frequently do you engage in the following activities?
(1) More than 4 (2) 4 to 2
Q: What is your work schedule?
Not Mutually Exclusive
1) Full-time
2) Part-time
How often do they think of work while at home.
Whether they have any hobbies.
How they spend their time off the job.
(3) Less than 2
Please answer using the following scale:
Assigning
a scale for
each
question.
(1: Often, 2: Sometimes, 3: Never)
A. Going to movies, theatre, concerts
B. Spending your weekend with your family
C. Coming together with friends
Scale
A set of symbols or numbers so constructed that the
symbols or numbers can be assigned by rule to the
individuals to whom the scale is applied.
• Series of items arranged according to value or
magnitude for the purpose of quantification
• Series of items are assigned by rule
• A continuous spectrum
NOMINAL
ORDINAL
INTERVAL
RATIO
Copyright © 2003 John Wiley & Sons, Inc. Sekaran/RESEARCH 4E
8F
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Example:
Rank the following five characteristics in a job in terms of how important they are for you.
You should rank the most important item as 1, the next in importance as 2, and so on.
Job Characteristics
Ranking the importance
Interact with others
...................
Use a number of different skills
...................
Complete a whole task from beginning to end
...................
Work independently
...................
Example:
At which market do you shop most frequently?
□ Kipa
□ Metro
□ Migros
□ Tansaş
□ Pehlivanoğlu
□ Other
8B
8C
Example:
Indicate the extent to which you agree with the following statements
as they relate to your job by using following scale
Strongly
Disagree
Disagree
Neither
Agree Nor
Disagree
Agree
Strongly
Agree
Working independetly is very important for me
1
2
3
4
5
Using different skills at job is very important
for me
1
2
3
4
5
Example:
What is your monthly household income?................................
8D
8E
Refreshments!...
Exercises
8G
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The Measuring Process
Ranking - Rank order preference
Rating - Estimates magnitude of a characteristic

Ranking tasks require that the respondent rank order a
small number of objects in overall performance on the
basis of some characteristic or stimulus.

Sorting might present the respondent with several
concepts typed on cards and require that the
respondent arrange the cards into a number of piles or
otherwise classify the concepts.
Sorting - Arrange or classify concepts
Choice - Selection of preferred alternative

Rating asks the respondent to estimate the magnitude of
a characteristic, or quality, that an object possesses. The
respondent’s position on a scale(s) is where he or she
would rate an object.
Simple Attitude Scaling

Choice between two or more alternatives
is another type of attitude measurement it is assumed that the chosen object is
preferred over the other.
 In its most basic form, attitude scaling requires that an individual
agree with a statement or respond to a single question. This type of
self-rating scale merely classifies respondents into one of two
categories;
THE PRESIDENT SHOULD RUN FOR RE-ELECTION
_______ AGREE
______ DISAGREE
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Category Scales


A category scale is a more sensitive measure than a scale having
Example of Category Scale
How important were the following in your decision to visit San Diego
(check one for each item)
only two response categories - it provides more information.
VERY
SOMEWHAT
NOT TOO
Questions working is an extremely important factor in the usefulness
IMPORTANT
IMPORTANT
IMPORTANT
CLIMATE
___________
___________
___________
COST OF TRAVEL
___________
___________
___________
FAMILY ORIENTED
___________
___________
___________
___________
___________
___________
___________
of these scales.
EDUCATIONAL/
HISTORICAL ASPECTS _________
FAMILIARITY WITH
AREA
The Likert Scale
___________
Likert Scale for Measuring Attitudes
Toward Tennis
 An extremely popular scale for measuring attitudes.
 Respondents indicate their own attitudes by checking how strongly
they agree or disagree with statements.
 Response alternatives:
 “strongly agree”, “agree”, “uncertain”, “disagree”, and “strongly disagree”.
Playing tennis is the best way to exercise.
___Strongly Agree
___Agree
___Not Sure
___Disagree
___Strongly Disagree
Semantic Differential
A series of seven-point bipolar rating scales.
Bipolar adjectives, such as “good” and “bad”,
anchor both ends (or poles) of the scale.
Semantic Differential Scales for
Measuring Attitudes Toward Tennis
Exciting ___ : ___ : ___ : ___ : ___ : ___ : ___ : Calm
Interesting ___ : ___ : ___ : ___ : ___ : ___ : ___ : Dull
Simple___ : ___ : ___ : ___ : ___ : ___ : ___ Complex
Passive ___ : ___ : ___ : ___ : ___ : ___ : ___ Active
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Numerical Scales
Numerical scales have numbers as response
options, rather than “semantic space’ or verbal
descriptions, to identify categories (response
positions).
Stapel Scales
 Modern versions of the Stapel scale place a single
adjective as a substitute for the semantic differential
when it is difficult to create pairs of bipolar adjectives.
 The advantage and disadvantages of a Stapel scale, as
well as the results, are very similar to those for a
semantic differential. However, the Stapel scale tends to
be easier to conduct and administer.
A Stapel Scale
for Measuring a Store’s Image
Department
Store Name
+3
+2
+1
Behavioral Differential Scale
The behavioral differential instrument has been developed for
measuring the behavioral intentions of subjects towards any object
or category of objects. A description of the object to be judged is
placed on the top of a sheet, and the subjects indicate their
behavioral intentions toward this object on a series of scales.
For example:
Wide Selection
-1
-2
-3
A 25-year old woman sales representative
Would ___ : ___ : ___ : ___ : ___ : ___ : ___ : Would Not
Ask this person for advice.
Graphic Rating Scales
Fixed or Constant Sum Scale

Divide 100 points among each of the following brands
according to your preference for the brand:
A graphic rating scale presents respondents with a
graphic continuum.
Brand A _________
Brand B _________
Brand C _________
3
Very
Good
2
1
Very
Poor
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Graphic Rating Scale Stressing
Pictorial Visual Communications
Example
Design a Likert type, semantic
differential type, staple type scale in
order to measure service quality level
of Faculty canteen.
3
Very
Good
2
1
Very
Poor
Reliability and Validity on Target
Low Reliability
(Target A)
High Reliability
(Target B)
Reliable but Not Valid
(Target C)
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