LECTURE 5.1

MEASUREMENT AND MANIPULATION

I. Variables: Anything that can take on different values

A. Stimuli: Flash of light, food, teaching methods

B. Responses: Motor activity, emotional experiences, bar presses, test performance

II. To be a science, psychology must develop operational definitions: A definition of a concept in terms of the operations used to produce it or in terms of the operations used to measure it.
Operational definitions reduce the potential for bias and allow other researchers to repeat your study.

III. Assessing Validity of a Measure

A. Usually, a measure must be reliable to be valid.

General types of reliability:

1. Inter-observer reliability

2. Test-retest reliability

3. Internal consistency

B. Some argue that first step in determining validity is to know what it is that we are trying to measure.

C. Content validity

D. Convergent validity

E. Discriminant validity

IV. Manipulating a variable

A. Search through

1. Textbooks

2. Psych Abstracts

B. Consult

1. Dictionary

2. Theory

C. Check to see if manipulation is

1. Ethical

2. Practical

3. Standardized

V. Evaluating a manipulation's validity

A. Consistent with theory or established definition

B. Manipulation check

C. Interview participants

D. Repeat study using different manipulation

Back to Chapter 5 Main Menu