BHS Research Methods and Biostatistics 2 — Questions and Answers
Question 1: What does a '95% confidence interval' represent in health research?
- A range of values within which the true population parameter is expected to fall 95% of the time with repeated sampling (Correct answer)
- A range where 95% of individual data points fall
- The probability that the study result is correct
- The precision of the measuring instrument used
Correct answer: A range of values within which the true population parameter is expected to fall 95% of the time with repeated sampling
A 95% confidence interval means that if the study were repeated many times, 95% of the calculated intervals would contain the true population value.
Question 2: Which study design is most useful for studying rare diseases or conditions with long latency periods?
- Case-control study (Correct answer)
- Cohort study
- Randomized controlled trial
- Cross-sectional study
Correct answer: Case-control study
Case-control studies start with people who already have the disease (cases) and compare their past exposures to disease-free controls, making them efficient for rare conditions.
Question 3: What is 'statistical power' in research design?
- The probability that a study will correctly detect a true effect when one exists (Correct answer)
- The number of participants required for meaningful results
- The ability to generalize results to other populations
- The strength of the association between variables
Correct answer: The probability that a study will correctly detect a true effect when one exists
Statistical power (1-β) is the probability of correctly rejecting a false null hypothesis; conventionally, studies aim for 80% power to minimize type II errors.
Question 4: What is the Belmont Report's principle of 'justice' in human subjects research?
- Fair distribution of the benefits and burdens of research across all population groups (Correct answer)
- The obligation to maximize benefits and minimize harms
- Respect for individuals' autonomy and right to make decisions
- Legal accountability of researchers for study outcomes
Correct answer: Fair distribution of the benefits and burdens of research across all population groups
Justice requires that the benefits and burdens of research are fairly distributed, ensuring vulnerable groups are neither exploited as subjects nor excluded from benefits.
Question 5: What is a 'confounder' in epidemiological research?
- A variable associated with both the exposure and outcome that distorts the true relationship between them (Correct answer)
- A factor that increases the precision of measurements
- A variable that mediates the causal pathway between exposure and disease
- An error introduced by the measurement instrument
Correct answer: A variable associated with both the exposure and outcome that distorts the true relationship between them
A confounder is a third variable that is associated with both the exposure and the outcome, potentially creating a spurious or masked association between the two.
Question 6: Which type of validity refers to whether a study's findings can be generalized to other populations or settings?
- External validity (Correct answer)
- Internal validity
- Construct validity
- Content validity
Correct answer: External validity
External validity (generalizability) refers to how well a study's findings apply to other populations, settings, or time periods beyond those studied.
BHS Research Methods and Biostatistics 2
What does a '95% confidence interval' represent in health research?