1. MEASUREMENT OF VARIABLES: OPERATIONAL DEFINITION AND SCALES
CHAPTER 8

2. HOW VARIABLES ARE MEASURED?
Two types of variables:
Variable that lends itself to objective and precise measurement
Variable that doesn’t lend itself to accurate measurement because of its subjective nature.
Abstract notions  observable characteristic behavior  measurable in a tangible way  called operationalizing the concepts
Operational definition is a statement of the specific dimensions and elements through which a concept will become measurable

3. OPERATIONAL DEFINITION: DIMENSIONS AND ELEMENTS

4. OPERATIONAL DEFINITION: DIMENSIONS AND ELEMENTS

5. SCALES very low very high
Nominal Scales: splits data into groups, e.g., men, women
Ordinal Scales: ranks data in some order, e.g., exercising for 20 minutes is good, for 30 minutes is better, for 40 minutes is best
Interval Scales: sets data on a continuum, e.g.
very low very high
Ratio Scales: starts with absolute zero and indicates proportion, e.g.
ten is twice as big as five

7. MEASUREMENT: SCALING, RELIABILITY, VALIDITY
CHAPTER 9

8. SCALING TECHNIQUES: 1. Rating Scales
Dichotomous Scales  yes or no answer
Category Scales  uses multiple items to elicit a single response
Likert Scales  to examine how strongly subjects agree or disagree with statement on a 5-point scale
Semantic Differential Scales  several bipolar attributes are identified at the extremes of the scale
Numerical Scales  similar with Semantic Differential Scales with number on 5 or 7 point scale are provided

9. SCALING TECHNIQUES: 1. Rating Scales…con’t
Itemized Rating Scales  a 5 or 7 point scale with anchors is provided for each item and the respondent state the appropriate number on the side of each item
Fixed or Constant Sum Rating Scales  the respondents are asked to distribute a given number of points across various items, the sum is constant
Stapel Scales  measure both direction and intensity of the attitude toward the item under study
Graphic Rating Scales  placing a mark at the appropriate point on the line

10. SCALING TECHNIQUES 2. Ranking Scales
Paired Comparisons  used when, among small number of objects, respondents are asked to choose between two objects at a time.
Forced Choice  enables respondents to rank objects relative to one another, among alternatives provided.
Comparative Scales provides a benchmark or a point of reference to assess attitude toward the current object, event, or situation under study.

11. GOODNESS OF MEASURES Stability Internal Consistency Validity
Test-retest reliability
Parallel-form reliability
Internal Consistency
Split-half reliability
Interitem consistency reliability
Validity
Content Validity
Face validity
Criterion-Related Validity
Concurrent validity
Predictive validity
Construct Validity