AP Experimental Methodology. Introduction. As a science, psychology uses the experimental method in order to establish a cause and effect relationship between two events (i.e. variables) The experimental method is the only way to prove that there is a cause and effect relationship.
Experimental group: receives the independent variable
Control Group: does not receive the independent variable
2) Longitudinal Study: researchers follow a group of people for a period of years (in some cases, decades), to study an aspect of their behavior (Framingham Heart Study, Hiroshima, National Children’s Study)
3)Surveys: Researchers question subjects on certain issues of interest
Example: Opinion polls
4) Correlational studies: Researchers look to see if there is a connection between two or more things.
Example: The more income you make, the more likely you will vote.
Important: correlation does not equal causation
In order to prove cause/effect relationship, the experimental method must be used
Positive Correlation: Increase in X is related with an increase in Y
Example: People with high GPAs have high ACT scores
Negative Correlation: Increase in X is related to a decrease in Y
Example: The more television a person watches, the fewer miles they walk/run.