ISSA Research Methods & Evidence-Based Practice 3 — Questions and Answers
Question 1: Which level of evidence is generally considered HIGHEST in the hierarchy of evidence-based nutrition?
- Expert opinion and consensus statements
- Single randomized controlled trial
- Systematic review and meta-analysis of RCTs (Correct answer)
- Prospective cohort study
Correct answer: Systematic review and meta-analysis of RCTs
Systematic reviews and meta-analyses that pool data from multiple well-conducted RCTs represent the highest quality evidence in the hierarchy.
Question 2: A researcher finds p = 0.03 for a dietary intervention study. Which conclusion is most accurate?
- There is a 3% chance the null hypothesis is true
- The result is statistically significant at α = 0.05 (Correct answer)
- The effect size is large
- The intervention is clinically meaningful
Correct answer: The result is statistically significant at α = 0.05
A p-value of 0.03 is below the conventional threshold of 0.05, indicating statistical significance, but this does not confirm clinical importance or large effect size.
Question 3: In a double-blind RCT on protein supplementation, who is blinded to the treatment assignment?
- Only the statistician analyzing data
- Only the participants
- Both participants and investigators administering the treatment (Correct answer)
- The IRB review board only
Correct answer: Both participants and investigators administering the treatment
Double-blind means neither the participants nor the researchers delivering or assessing the intervention know who received the active treatment or placebo.
Question 4: Heterogeneity in a meta-analysis is commonly assessed using which statistic?
- Odds ratio
- I² statistic (Correct answer)
- Hazard ratio
- Beta coefficient
Correct answer: I² statistic
The I² statistic quantifies the percentage of total variation across studies that is due to heterogeneity rather than chance.
Question 5: Which term describes a systematic error that consistently skews study results in one direction?
- Random error
- Confounding
- Bias (Correct answer)
- Effect modification
Correct answer: Bias
Bias is a systematic error that leads to an over- or underestimate of the true association, unlike random error which affects precision.
Question 6: What is a confounder in nutrition research?
- An outcome variable that mediates the relationship
- A variable associated with both the exposure and outcome that distorts the true relationship (Correct answer)
- A second dependent variable measured alongside the primary outcome
- A statistical test used to control for multiple comparisons
Correct answer: A variable associated with both the exposure and outcome that distorts the true relationship
A confounder is an extraneous variable that correlates with both the exposure and the outcome, potentially creating a spurious or masked association.
Question 7: In evidence-based practice, applying research findings to an individual client requires consideration of:
- Only the statistical significance of study results
- Clinical expertise, patient values, and best available evidence (Correct answer)
- The sample size of the primary study alone
- The funding source of the research
Correct answer: Clinical expertise, patient values, and best available evidence
Evidence-based practice integrates the best research evidence with clinical expertise and the individual client's preferences, values, and circumstances.
ISSA Research Methods & Evidence-Based Practice 3
Which level of evidence is generally considered HIGHEST in the hierarchy of evidence-based nutrition?