NP Research & Evidence-Based Practice 2 — Questions and Answers
Question 1: A nurse practitioner is critically appraising a randomized controlled trial. Which element most directly addresses internal validity?
- Adequate allocation concealment (Correct answer)
- Large sample size from multiple sites
- Use of validated outcome measures
- Long follow-up period
Correct answer: Adequate allocation concealment
Allocation concealment prevents selection bias by ensuring assignment is hidden until enrollment, directly protecting internal validity.
Question 2: When using the PICO framework, what does the 'C' component represent?
- Comparison or control intervention (Correct answer)
- Clinical context of the patient
- Confidence interval of the result
- Cost-effectiveness of treatment
Correct answer: Comparison or control intervention
In PICO, 'C' stands for Comparison, the alternative intervention or control against which the intervention is measured.
Question 3: A study reports a relative risk of 0.60 for a new antihypertensive drug. How should an NP interpret this finding?
- The treatment group had 40% lower risk of the outcome than the control group (Correct answer)
- The treatment group had 60% lower risk of the outcome than the control group
- The treatment reduced absolute risk by 40%
- The treatment was 60% effective in preventing the outcome
Correct answer: The treatment group had 40% lower risk of the outcome than the control group
A relative risk of 0.60 means the treatment group's risk is 60% of the control group's risk, representing a 40% relative risk reduction.
Question 4: Which type of bias occurs when patients who are lost to follow-up differ systematically from those who complete a study?
- Attrition bias (Correct answer)
- Detection bias
- Performance bias
- Reporting bias
Correct answer: Attrition bias
Attrition bias (also called withdrawal bias) occurs when systematic differences exist between participants who drop out and those who remain.
Question 5: An NP wants to find the highest-quality pre-appraised evidence quickly. Which resource is most appropriate?
- Cochrane Database of Systematic Reviews (Correct answer)
- MEDLINE database search
- UpToDate clinical decision support
- A single recent RCT
Correct answer: Cochrane Database of Systematic Reviews
Cochrane systematic reviews represent the gold standard for pre-appraised, synthesized evidence and are designed to minimize bias.
Question 6: In a meta-analysis forest plot, what does a diamond that crosses the line of no effect indicate?
- The pooled result is not statistically significant (Correct answer)
- The studies had significant heterogeneity
- The pooled effect size is clinically significant
- The confidence interval is too narrow
Correct answer: The pooled result is not statistically significant
When the diamond (representing pooled effect and its CI) crosses the line of no effect (typically 1.0 for RR or 0 for MD), the result is not statistically significant.
Question 7: A qualitative study uses purposive sampling. What is the primary purpose of this approach?
- To select participants who can provide rich, relevant information about the phenomenon (Correct answer)
- To ensure the sample is statistically representative of the population
- To eliminate researcher bias in participant selection
- To maximize the number of participants enrolled
Correct answer: To select participants who can provide rich, relevant information about the phenomenon
Purposive sampling intentionally selects information-rich participants who have direct experience with the phenomenon being studied.
NP Research & Evidence-Based Practice 2
A nurse practitioner is critically appraising a randomized controlled trial.
Which element most directly addresses internal validity?