Measuring and Manipulating Variables

Question 1

Operational definition

Answer 1

• Define how variable is to be measured (within our experiment)
• Allows others to repeat experiment precisely
• Reduces generality of interpretations

Question 2

Delayed gratification

Answer 2

Amount of time willing to wait for reward

Question 3

Deciding how to operationalize

Answer 3

• Use operational variables that have worked in other studies
• Select operational definition that best fits what you really want to test

Question 4

Common types of IVs

Answer 4

1. Manipulated variables

2. Subject variables

Question 5

Manipulated variables

Answer 5

• Situational variables (bystander effect)
• Task variables (diff. levels of IV)
• Instructional variables (by differing instructions)
• Effect of ‘treatment’ (therapy vs. no therapy)

Question 6

Subject variables

Answer 6

Age, gender, etc.

-Varies by the subject

Question 7

Common types of DVs

Answer 7

1. Self-reporting measures
2. Behavioral measures
3. Physiological Measures
4. Indirect dependent variable

Question 8

Self-reporting measures

Answer 8

• Rating scales

- Opinion polls/ questionnaires

Question 9

Behavioral measures

Answer 9

• Accuracy or speed response
• Frequency of response
• Verbal responses

Question 10

Physiological Measures

Answer 10

• Way to operationalize person’s inner state
• Heart rate, bp
• Functional brain imaging (brain activity)

Question 11

Indirect dependent variable

Answer 11

Use observable behavior to measure something unobservable

Question 12

A given experiment can use (DV)

Answer 12

• A single DV
• Two + separate DVs
• Composite DV (several measures combined into single DV – intelligence)

Question 13

Criteria for selecting variables

Answer 13

• Must be reliable (repeatable with same results- does NOT mean accurate)
• Must be valid (measure what was intended to measure)

Question 14

Causes of unreliability- assess using

Answer 14

• Variations in how measure is administered – test-retest correlation
• Variations in scoring or data recording – inter-rater correlation
• Subject performance variations – split-half correlation

Question 15

How to establish a measure’s validity

Answer 15

1. Face Validity
2. Discriminant Validity
3. Concurrent Validity
4. Content Validity
5. Predictive Validity

Question 16

Face Validity

Answer 16

• Appears to be valid

- Weakest type of validity

Question 17

Discriminant Validity

Answer 17

• What else might be measured other than what you intended?

- Show that your measure DOES NOT correlate with the other factor

Question 18

Concurrent Validity

Answer 18

-Showing your measure DOES correlate with another measure of the same thing
OR
-Show two groups differ in your measure when they should differ

Question 19

Content Validity

Answer 19

Measure should accurately SAMPLE content it’s supposed to measure

Question 20

Predictive Validity

Answer 20

Show you measure accurately predicts what it ought to predict