| Research Method | Basic Purpose | How Conducted | What Is Manipulated | Weaknesses |
|---|
| Descriptive | To observe and record behavior | Do case studies, naturalistic observations, or surveys | Nothing | No control of variables; single cases may be misleading. |
| Correlational | To detect naturally occurring relationships; to assess how well one variable predicts another | Collect data on two or more variables; no manipulation | Nothing | Does not specify cause and effect. |
| Experimental | To explore cause and effect | Manipulate one or more factors; use random assignment | The independent variable(s) | Sometimes not possible for practical or ethical reasons. |