Certified Midwife Exam Prep Research & Evidence-Based Practice 2 — Questions and Answers
Question 1: A midwife reads a cohort study showing that women who receive continuous labor support have shorter labors. What is the PRIMARY limitation of this study design?
- Cannot establish causation due to lack of randomization (Correct answer)
- Sample sizes are always too small
- Cohort studies cannot measure labor duration
- The control group is unethical in this context
Correct answer: Cannot establish causation due to lack of randomization
Cohort studies observe outcomes over time but lack randomization, so confounding variables may explain the association rather than true causation.
Question 2: When critically appraising a clinical practice guideline, which element MOST indicates the guideline is evidence-based?
- It was written by a large professional organization
- Each recommendation is linked to a specific level of evidence (Correct answer)
- The guideline was published within the last 10 years
- It includes a comprehensive reference list
Correct answer: Each recommendation is linked to a specific level of evidence
Linking each recommendation to a graded level of evidence (e.g., Grade A, B, C) demonstrates that the guideline is systematically evidence-based.
Question 3: A systematic review reports a pooled odds ratio of 0.65 (95% CI: 0.45–0.94) for perineal trauma with water birth versus land birth. How should this finding be interpreted?
- Water birth significantly increases perineal trauma risk
- Water birth is associated with a statistically significant reduction in perineal trauma (Correct answer)
- The result is not statistically significant because CI crosses 1.0
- An OR below 1.0 means the outcome is more common in the control group
Correct answer: Water birth is associated with a statistically significant reduction in perineal trauma
An OR of 0.65 with a 95% CI that does not include 1.0 (0.45–0.94) indicates a statistically significant reduction in perineal trauma with water birth.
Question 4: Which research design is BEST suited to determine the incidence of gestational diabetes in a defined population over five years?
- Case-control study
- Cross-sectional study
- Prospective cohort study (Correct answer)
- Randomized controlled trial
Correct answer: Prospective cohort study
A prospective cohort study follows a population forward in time, making it ideal for calculating incidence rates of conditions like gestational diabetes.
Question 5: A midwife wants to change her practice based on a single randomized controlled trial. According to EBP hierarchy, what should she do FIRST?
- Implement the change immediately since RCTs are the gold standard
- Search for systematic reviews or meta-analyses on the same topic (Correct answer)
- Conduct her own replication study before changing practice
- Consult only expert opinion before acting
Correct answer: Search for systematic reviews or meta-analyses on the same topic
Systematic reviews and meta-analyses synthesize multiple RCTs and rank higher in the evidence hierarchy than a single RCT.
Question 6: In a research article, the p-value for a primary outcome is reported as p = 0.03. What does this mean?
- There is a 3% chance the null hypothesis is true
- There is a 97% probability the alternative hypothesis is correct
- If the null hypothesis were true, there is a 3% chance of obtaining results this extreme or more extreme (Correct answer)
- The effect size is clinically meaningful
Correct answer: If the null hypothesis were true, there is a 3% chance of obtaining results this extreme or more extreme
A p-value represents the probability of observing the results (or more extreme) assuming the null hypothesis is true, not the probability that the hypothesis itself is true or false.
Question 7: Which of the following BEST describes the concept of number needed to treat (NNT)?
- The percentage of patients who benefit from a treatment
- The number of patients who must receive treatment for one additional patient to benefit (Correct answer)
- The ratio of treatment responders to non-responders
- The minimum sample size required for a clinical trial
Correct answer: The number of patients who must receive treatment for one additional patient to benefit
NNT is the inverse of absolute risk reduction and tells clinicians how many patients must be treated to prevent one additional adverse outcome.
Certified Midwife Exam Prep Research & Evidence-Based Practice 2
A midwife reads a cohort study showing that women who receive continuous labor support have shorter labors.
What is the PRIMARY limitation of this study design?