BMAT Research & Evidence-Based Practice 4 — Questions and Answers
Question 1: A researcher reports a p-value of 0.03 for a primary outcome. Which statement is most accurate?
- There is a 3% probability the null hypothesis is true
- If the null hypothesis were true, results this extreme would occur 3% of the time by chance (Correct answer)
- The study has 97% statistical power
- The treatment effect is clinically significant
Correct answer: If the null hypothesis were true, results this extreme would occur 3% of the time by chance
A p-value is the probability of observing results at least as extreme as those obtained, assuming the null hypothesis is true.
Question 2: Which bias occurs when participants in a study change their behavior because they know they are being observed?
- Recall bias
- Hawthorne effect (Correct answer)
- Attrition bias
- Information bias
Correct answer: Hawthorne effect
The Hawthorne effect describes behavioral change in participants who are aware of being studied, potentially distorting results.
Question 3: Specificity in a diagnostic test is defined as the proportion of:
- True positives among all those with the disease
- True negatives among all those without the disease (Correct answer)
- Positive test results that are truly positive
- Negative test results that are truly negative
Correct answer: True negatives among all those without the disease
Specificity = TN / (TN + FP), measuring how well the test correctly identifies people who do not have the disease.
Question 4: An ecological study finds a correlation between national sugar consumption and diabetes rates. The main limitation of this finding is:
- It cannot establish incidence rates
- Individual-level data are not used, so ecological fallacy may apply (Correct answer)
- The study design cannot be replicated
- Ecological studies cannot control for confounders
Correct answer: Individual-level data are not used, so ecological fallacy may apply
The ecological fallacy is the error of inferring individual-level relationships from group-level (aggregate) data.
Question 5: Which of the following study designs is most appropriate for estimating disease prevalence in a population?
- Randomized controlled trial
- Case-control study
- Cross-sectional survey (Correct answer)
- Cohort study
Correct answer: Cross-sectional survey
Cross-sectional surveys measure disease status and exposures at one point in time, making them ideal for estimating prevalence.
Question 6: When a 95% confidence interval for an odds ratio includes 1.0, it indicates:
- The odds ratio is clinically meaningless
- The result is statistically significant at p < 0.05
- The result is not statistically significant at p < 0.05 (Correct answer)
- The study was underpowered
Correct answer: The result is not statistically significant at p < 0.05
A 95% CI that includes 1.0 means we cannot reject the null hypothesis of no association at the 5% significance level.
Question 7: In research ethics, the principle of 'beneficence' requires researchers to:
- Ensure participants are treated equally regardless of outcome
- Maximize potential benefits and minimize harms to participants (Correct answer)
- Obtain informed consent from all participants
- Protect the confidentiality of participant data
Correct answer: Maximize potential benefits and minimize harms to participants
Beneficence obligates researchers to actively promote participant welfare by maximizing benefits and minimizing risks of harm.
BMAT Research & Evidence-Based Practice 4
A researcher reports a p-value of 0.03 for a primary outcome.
Which statement is most accurate?