1. Chapter 4: Studying Behavior

2. Variables A variable is any event, situation, or behavior that varies.
Four general classifications
Situational variables describe characteristics of the environment.
Response variables are the responses or behaviors of individuals.

3. Variables (con’t)
Participant or subject variables are individual differences.
Mediating variables are psychological processes that mediate the effects of a situational variable on a particular response.

4. Which of the following is NOT a variable?
(Imagine game show music playing now…)
Hair color
Inches in a foot
Weight
Attitudes on gun control
Intelligence scores

5. Operational Definitions of Variables
Variable is an abstract concept that must be translated into concrete forms of observation or manipulation.
A variable must be defined in terms of the specific method used to measure or manipulate it this is called the operational definition.

6. Relationships Between Variables
Relationships between two variables
Do the levels of the two variables vary
systematically together?
Example:
As the number of days absent increases, do grades in the class decrease also?

7. Relationships Between Variables (con’t)
For the purposes of describing relationships, we will use variables that have true numeric properties.
Interval scale of measurement
Ratio scale of measurement

8. Relationships Between Variables (con’t)
Positive linear relationship (covary in the
same direction).
y-axis
x-axis OR

9. Relationships Between Variables (con’t)
Negative linear relationship (covary in opposite
directions)
y-axis
x-axis

10. Relationships Between Variables (con’t)

11. Relationships Between Variables (con’t)
Relationships and reduction of uncertainty
Uncertainty implies randomness
Random variability or error variance
Research is aimed at reducing random variability
by identifying systematic relationships between
variables.

12. Nonexperimental Versus Experimental Methods
Nonexperimental method
Relationships studied using observations or
measures of the variables of interest
Sometimes referred to as the correlational method
Problems with making causal statements using this
method

13. Nonexperimental Versus Experimental Methods
Nonexperimental method (con’t)
Two problems with making causal statements
Direction of cause and effect
Third variable problem

14. Nonexperimental Versus Experimental Methods
One variable is manipulated and the other variable
measured
Eliminates the third variable problem (confounding)
Experimental control
Randomization (random assignment)

15. Nonexperimental Versus Experimental Methods

16. Independent and Dependent Variables
Independent variable
Manipulated variable (cause)
Dependent variable
Measured variable (effect)

17. Independent and Dependent Variables (con’t)
y-axis
Independent variable
x-axis

18. Causality The inferences of cause and effect require three elements
Temporal order
Covariation between the two variables
3. Need to eliminate plausible alternative explanations

19. Choosing A Method: Advantages of Multiple Methods
Experimental versus nonexperimental methods
Considerations
Artificiality
- Field experiment versus lab experiment; weighing the advantages and disadvantages of each
Ethical and practical issues
- nonexperimental methods may be necessary
- ex post facto design

20. Choosing A Method: Advantages of Multiple Methods
3. Participant variables
4. Description of behavior
5. Successful predictions for the future
6. Advantages of multiple methods

21. Evaluating Research: Three Validities
Construct validity – the adequacy of the operational definitions
Internal validity – the ability to draw conclusions about causal relationships
External validity – the extent to which the results can be generalized to other populations and settings

22. The End