What the exam asks
- Section I (Multiple Choice): Standalone and set-based scenarios ask you to identify the target population and sample, spot sampling bias or convenience sampling, and distinguish between random sampling and random assignment.
- Section II (AAQ Part E): Every AAQ includes a Participants section (often with a demographic table) and asks you to state the extent to which the findings can be generalized to a population, backed by specific participant variables from the text.
Core ideas
Populations, samples and sampling methods
A population is the entire group of individuals a researcher wants to understand (e.g., all high school athletes in the United States). A sample is the smaller subset of individuals actually selected from that population to participate in the study.
For results to apply accurately to the population, the sample must be a representative sample—one whose demographic makeup (age, gender, race, socioeconomic status, location) closely mirrors the population of interest.
| Concept | Definition | Primary Purpose |
|---|---|---|
| Random sampling | Every member of the target population has an equal chance of being selected for the study (e.g., using a random number generator on a full roster). | Increases representativeness and allows generalizability to the population. |
| Convenience sampling | Selecting participants who are readily available (e.g., surveying students in the researcher’s own introductory psychology class). | Fast and inexpensive, but typically creates an unrepresentative sample. |
| Sampling bias | A flaw in the selection process where some members of the population are systematically more likely to be chosen than others (including self-selection/volunteer bias). | Reduces generalizability because the sample differs systematically from the population. |
| Random assignment | Placing already-selected participants into experimental and control groups by chance (e.g., flipping a coin). | Equalizes preexisting participant differences across groups to allow causal conclusions in experiments. |