HSP Research and Scientific Foundations 3 — Questions and Answers
Question 1: A health psychologist conducting a single-case experimental design uses an ABAB withdrawal design. The primary purpose of the second return to baseline (B) is to:
- Assess generalization of treatment effects across settings
- Demonstrate experimental control by replicating the intervention effect (Correct answer)
- Estimate the test-retest reliability of the outcome measure
- Reduce regression to the mean in the outcome variable
Correct answer: Demonstrate experimental control by replicating the intervention effect
The second intervention phase in an ABAB design replicates the effect, demonstrating that behavior change is functionally related to the treatment.
Question 2: A researcher reports a 95% confidence interval of [0.10, 0.45] for a risk ratio. The correct interpretation is:
- There is a 95% probability that the true ratio is in this interval for this sample
- If the study were repeated, 95% of such intervals would contain the true population parameter
- The result is statistically significant at α = .05 because 1.0 is excluded
- Both B and C are correct interpretations (Correct answer)
Correct answer: Both B and C are correct interpretations
A 95% CI means 95% of such intervals capture the true parameter (frequentist interpretation), and excluding 1.0 confirms significance at α = .05 for a ratio.
Question 3: Which of the following threats to internal validity involves participants changing over the course of a study due to natural developmental processes?
- History
- Maturation (Correct answer)
- Instrumentation
- Selection bias
Correct answer: Maturation
Maturation refers to natural changes in participants over time (e.g., aging, fatigue) that may explain outcome differences independent of the intervention.
Question 4: In multiple regression, multicollinearity is most problematic because it:
- Inflates Type I error rates for the overall F-test
- Increases standard errors of individual regression coefficients (Correct answer)
- Violates the assumption of normally distributed residuals
- Reduces the R² of the model to near zero
Correct answer: Increases standard errors of individual regression coefficients
Multicollinearity inflates standard errors of regression coefficients, making individual predictors appear non-significant even when they have real effects.
Question 5: The Belmont Report's principle of 'beneficence' in research ethics refers to:
- Ensuring fair distribution of research burdens and benefits across populations
- Maximizing potential benefits and minimizing possible harms to participants (Correct answer)
- Respecting participants' autonomy to make voluntary informed decisions
- Maintaining confidentiality of participant data after study completion
Correct answer: Maximizing potential benefits and minimizing possible harms to participants
Beneficence obligates researchers to maximize participant benefits and minimize risks, going beyond simply doing no harm.
Question 6: A meta-analysis detects significant heterogeneity (I² = 78%). The most appropriate next step is:
- Exclude all studies with wide confidence intervals
- Conduct moderator analyses to identify sources of variability (Correct answer)
- Report only the random-effects pooled estimate without further analysis
- Convert the analysis to a narrative synthesis and discard quantitative pooling
Correct answer: Conduct moderator analyses to identify sources of variability
High I² warrants moderator analyses (meta-regression or subgroup analysis) to identify study characteristics that explain the variability in effect sizes.
Question 7: A psychologist administers the same measure twice to the same group two weeks apart and finds r = .91. This primarily reflects:
- Parallel-forms reliability
- Internal consistency
- Test-retest reliability (Correct answer)
- Inter-rater reliability
Correct answer: Test-retest reliability
Test-retest reliability (temporal stability) is measured by correlating scores from the same instrument administered to the same participants at two time points.
HSP Research and Scientific Foundations 3
A health psychologist conducting a single-case experimental design uses an ABAB withdrawal design.
The primary purpose of the second return to baseline (B) is to: