APA Research Methods and Statistics 2 — Questions and Answers
Question 1: A researcher measures anxiety before and after a treatment in the same group. Which statistical test is most appropriate?
- Independent-samples t-test
- Chi-square test
- Paired-samples t-test (Correct answer)
- One-way ANOVA
Correct answer: Paired-samples t-test
The paired-samples (dependent) t-test compares means from two related measurements taken from the same participants.
Question 2: What does internal validity refer to in psychological research?
- Whether findings generalize to the real world
- Whether a test measures what it claims to measure
- The degree to which changes in the DV are caused by the IV (Correct answer)
- Consistency of results across studies
Correct answer: The degree to which changes in the DV are caused by the IV
Internal validity concerns whether observed changes in the dependent variable are genuinely caused by manipulation of the independent variable, ruling out confounds.
Question 3: Which sampling method gives every member of the population an equal chance of being selected?
- Convenience sampling
- Quota sampling
- Simple random sampling (Correct answer)
- Purposive sampling
Correct answer: Simple random sampling
Simple random sampling uses a process (e.g., lottery or random number generator) that gives each population member an equal probability of selection.
Question 4: In APA Publication Manual format, how should a statistically non-significant result be reported?
- p > .05 with actual p-value, e.g., p = .21 (Correct answer)
- NS without further detail
- p = 1.00
- The result should be omitted
Correct answer: p > .05 with actual p-value, e.g., p = .21
APA recommends reporting the exact p-value regardless of significance (e.g., p = .21) rather than only noting p > .05 or 'NS'.
Question 5: What is the main advantage of a within-subjects design over a between-subjects design?
- It eliminates order effects
- It requires fewer participants and reduces error variance (Correct answer)
- It allows for larger sample sizes
- It prevents attrition
Correct answer: It requires fewer participants and reduces error variance
Within-subjects designs use each participant as their own control, reducing individual-difference error and requiring fewer total participants.
Question 6: Which type of reliability refers to consistency of a measure across different raters?
- Test-retest reliability
- Internal consistency
- Inter-rater reliability (Correct answer)
- Parallel-forms reliability
Correct answer: Inter-rater reliability
Inter-rater reliability (also called inter-observer reliability) measures the degree to which different raters agree in their assessments or coding.
APA Research Methods and Statistics 2
A researcher measures anxiety before and after a treatment in the same group.
Which statistical test is most appropriate?