1. Experimental Research Method Versus Correlational Research Methods
AP Psych FRQ Review
Experimental Research Method Versus Correlational Research Methods

2. Experimental Method
Experiments are carefully controlled experiments that can show a causal relationship between variables
Contains an independent variable and a dependent variable

3. Experimental Method
Hypothesis = expressing a relationship between 2 variables:
Independent variable = the variable being manipulated to try to cause a change
Dependent variable = depends on the independent variable
A change in the independent variable will produce a change in the dependent variable

4. Example
The hypothesis (expression of a relationship between two variables) that playing violent video games makes people more likely to have a positive attitude toward real-life violence
What is the independent variable?
What is the dependent variable?

5. Independent variable = playing violent video games (the hypothesis suggests that a change in playing violent video games will result in a change in attitude).
Dependent variable = the attitude toward violence (depends on playing violent video games)

6. Operational Definitions of Variables
How are you measuring the variables?
Example: What video games are considered violent? What attitudes are considered positive toward / favoring violence?

7. Experimental Method: Controlling for Confounding Variables
Confounding variable = any difference other than the independent variable that may affect the dependent variable
Divide into experimental and control groups (assign participants to conditions) to control for confounding variables

8. Experimental v. Control Group
Experimental group = the one that receives the treatment from the independent variable
Control group = does not get any of the independent variable
Example: experimental group = plays violent video games; control group = does not play violent video games

9. Correlational Studies
Investigate the same variables as experimental studies, but do not use the terminology independent and dependent variable because do not reveal cause-effect relationships

10. Correlational Studies
Do not divide participants into separate groups based on the independent variable
Most commonly use surveys to obtain data
Easier, but cannot control for confounding variables like in an experimental study

11. Correlational Studies
Can only predict the relationship between two variables!
Cannot attribute causation!
Ex. cannot say that playing violent video games causes people to have positive attitudes toward violence

12. Correlational Studies and Predictions
Positive correlation = one variable increases as other variable increases (positive correlation)
Negative correlation = one variable decreases as other increases
No relationship between variables = zero / no correlation

13. Experimental Studies and Cause
An experimental study can state that the independent variable causes dependent variable to change…ex playing violent games causes more positive attitudes about violence