What the exam asks
On the AP Psychology exam, you must be ready to:
- Verify an experiment: Determine whether a study is a true experiment by checking for both a manipulated independent variable and random assignment (AAQ Part A and MCQ sets).
- Write and evaluate operational definitions: State exactly how a variable was measured or quantified in a study so another researcher could replicate it (AAQ Part B).
- Unpack research scenarios: Identify the hypothesis, independent variable (IV), dependent variable (DV), confounding variables, experimental group, and control group.
- Select experimental controls: Explain how random assignment, placebos, and single- or double-blind procedures prevent participant and experimenter biases.
- Classify measurements: Distinguish between quantitative instruments (like Likert scales) and qualitative instruments (like structured interviews).
Core ideas
1. Hypotheses and falsifiability
A hypothesis is a testable prediction about the relationship between two or more variables, often derived from a broader psychological theory. For a hypothesis to be scientific, it must be falsifiable—meaning there must be a possible outcome gathered through empirical data that could prove the prediction wrong.
- Falsifiable: “Students who sleep 8 hours before a test will score higher on a 50-question vocabulary quiz than students who sleep 4 hours.”
- Unfalsifiable: “People make poor decisions because of invisible, unmeasurable forces from their past.”
2. Variables and operational definitions
An experiment tests whether manipulating one factor causes a change in another.
| Variable Type | Role in the Study | Quick Question to Ask |
|---|---|---|
| Independent Variable (IV) | The factor the researcher actively manipulates or varies across conditions. | What did the researcher change on purpose? |
| Dependent Variable (DV) | The outcome factor measured to see if it changes in response to the IV. | What data did the researcher collect at the end? |
| Confounding Variable | An outside factor (other than the IV) that varies systematically between groups and could affect the DV. | What else differed between the groups that ruins the causal claim? |
An operational definition specifies the exact, measurable, or quantifiable procedures used to manipulate the IV or measure the DV in a specific study. Clear operational definitions allow other scientists to replicate (repeat) the study with different participants to verify the findings.