NBCE Research and Development 3 — Questions and Answers
Question 1: Which sampling method ensures every member of a population has an equal chance of being selected?
- Convenience sampling
- Purposive sampling
- Simple random sampling (Correct answer)
- Snowball sampling
Correct answer: Simple random sampling
Simple random sampling gives every individual in the population an equal and independent chance of inclusion.
Question 2: Institutional Review Board (IRB) approval is primarily required to:
- Validate the statistical methodology of a study
- Protect the rights and welfare of human research subjects (Correct answer)
- Ensure funding compliance with federal grant requirements
- Peer review the scientific quality of the research protocol
Correct answer: Protect the rights and welfare of human research subjects
IRBs exist to safeguard the rights, privacy, and welfare of individuals participating in research.
Question 3: In a study with p = 0.03, the correct interpretation is:
- There is a 3% probability the null hypothesis is true
- There is a 97% probability the alternative hypothesis is true
- If the null hypothesis were true, results this extreme would occur 3% of the time by chance (Correct answer)
- The effect size is clinically meaningful at a 3% threshold
Correct answer: If the null hypothesis were true, results this extreme would occur 3% of the time by chance
The p-value represents the probability of obtaining results as extreme as observed, assuming the null hypothesis is true.
Question 4: Construct validity in chiropractic outcomes research refers to:
- The degree to which a measure consistently produces the same results
- Whether an instrument truly measures the theoretical construct it claims to measure (Correct answer)
- The extent to which results can be applied to other populations
- Agreement between two different raters using the same instrument
Correct answer: Whether an instrument truly measures the theoretical construct it claims to measure
Construct validity assesses whether an instrument accurately captures the theoretical concept it is designed to measure.
Question 5: Which measure of central tendency is most resistant to extreme outlier values in a dataset?
- Mean
- Variance
- Median (Correct answer)
- Standard deviation
Correct answer: Median
The median is not influenced by extreme values and is therefore more robust than the mean in skewed distributions.
Question 6: A chiropractic researcher uses a crossover design, which means:
- Two separate patient groups receive different treatments simultaneously
- Each participant serves as their own control by receiving both treatments sequentially (Correct answer)
- Researchers switch from qualitative to quantitative methods mid-study
- Subjects are randomly allocated to control versus experimental groups
Correct answer: Each participant serves as their own control by receiving both treatments sequentially
In a crossover design, each participant receives both treatments in different periods, serving as their own control.
Question 7: Publication bias in systematic reviews most commonly results in:
- Overrepresentation of studies with negative or null findings
- Exclusion of foreign-language studies from the analysis
- Overestimation of treatment effects due to selective reporting of positive results (Correct answer)
- Reduced statistical power to detect true differences
Correct answer: Overestimation of treatment effects due to selective reporting of positive results
Positive results are more likely to be published, causing systematic reviews to overestimate actual treatment benefit.
NBCE Research and Development 3
Which sampling method ensures every member of a population has an equal chance of being selected?