ABFM Research Methods & Evidence-Based Practice 2 — Questions and Answers
Question 1: In forensic research, which study design provides the highest level of evidence for establishing causation?
- Case series
- Cross-sectional study
- Randomized controlled trial (Correct answer)
- Expert opinion
Correct answer: Randomized controlled trial
Randomized controlled trials minimize confounding through random assignment and are at the top of the evidence hierarchy for establishing causation.
Question 2: A forensic pathologist reviews 15 years of toxicology reports to identify trends in opioid-related deaths. This is an example of which research design?
- Prospective cohort study
- Retrospective cohort study (Correct answer)
- Case-control study
- Ecological study
Correct answer: Retrospective cohort study
A retrospective cohort study uses existing records to follow subjects from past exposure to outcome, which describes reviewing historical toxicology data for trends.
Question 3: Which statistical measure best describes the strength of association between a risk factor and an outcome in a case-control study?
- Relative risk
- Odds ratio (Correct answer)
- Attributable risk
- Number needed to treat
Correct answer: Odds ratio
Odds ratios are the appropriate measure of association in case-control studies because incidence rates cannot be directly calculated from this design.
Question 4: A researcher finds p=0.03 for a study comparing two forensic toxicology methods. What does this mean?
- There is a 3% chance the null hypothesis is true
- There is a 3% probability of observing results this extreme if the null hypothesis were true (Correct answer)
- The effect size is clinically meaningful
- The study has 97% power
Correct answer: There is a 3% probability of observing results this extreme if the null hypothesis were true
A p-value represents the probability of obtaining results at least as extreme as observed, assuming the null hypothesis is true.
Question 5: When appraising a forensic medicine study for bias, which type occurs when cases are identified differently from controls in a case-control study?
- Selection bias
- Information bias (Correct answer)
- Confounding
- Attrition bias
Correct answer: Information bias
Information bias (including recall bias and misclassification) arises from systematic differences in how data are collected or recorded between comparison groups.
Question 6: A systematic review of forensic age estimation studies shows an I² statistic of 78%. How should this be interpreted?
- 78% of studies had methodological flaws
- 78% of total variability is due to heterogeneity rather than chance (Correct answer)
- The pooled estimate is reliable
- 78% of confidence interval width is from bias
Correct answer: 78% of total variability is due to heterogeneity rather than chance
The I² statistic quantifies the proportion of total variation in effect estimates attributable to heterogeneity between studies rather than sampling error.
Question 7: In forensic epidemiology, which concept refers to the proportion of disease in the exposed group attributable to the exposure itself?
- Population attributable risk
- Attributable risk percent in the exposed (Correct answer)
- Relative risk
- Incidence rate ratio
Correct answer: Attributable risk percent in the exposed
Attributable risk percent in the exposed (also called etiologic fraction) estimates the proportion of disease among exposed individuals that is due to the exposure.
ABFM Research Methods & Evidence-Based Practice 2
In forensic research, which study design provides the highest level of evidence for establishing causation?