CRC Research Methods 2 — Questions and Answers
Question 1: A researcher wants to determine whether a new vocational training program causes better employment outcomes compared to no training. Which research design best supports a causal inference?
- Correlational study
- Randomized controlled trial (Correct answer)
- Case study
- Archival research
Correct answer: Randomized controlled trial
A randomized controlled trial uses random assignment to control for confounds, making causal inference possible.
Question 2: In a study measuring depression before and after a counseling intervention using the same instrument, which type of validity is most threatened by participants recalling their previous answers?
- Construct validity
- External validity
- Internal validity due to testing effects (Correct answer)
- Content validity
Correct answer: Internal validity due to testing effects
Testing effects (a threat to internal validity) occur when prior exposure to a measure influences later scores.
Question 3: Which sampling method divides the population into subgroups and then randomly selects participants from each subgroup proportionally?
- Cluster sampling
- Systematic sampling
- Stratified random sampling (Correct answer)
- Purposive sampling
Correct answer: Stratified random sampling
Stratified random sampling ensures proportional representation by randomly sampling within defined subgroups.
Question 4: A Likert-scale instrument produces which level of measurement?
- Nominal
- Ratio
- Ordinal (Correct answer)
- Interval
Correct answer: Ordinal
Likert scales produce ordinal data because the distances between response options are not guaranteed to be equal.
Question 5: When a researcher selects participants because they are easily accessible rather than through a probability method, this is called:
- Snowball sampling
- Convenience sampling (Correct answer)
- Quota sampling
- Cluster sampling
Correct answer: Convenience sampling
Convenience sampling selects participants based on availability, limiting generalizability.
Question 6: A Type II error in hypothesis testing occurs when a researcher:
- Rejects a true null hypothesis
- Fails to reject a false null hypothesis (Correct answer)
- Uses the wrong statistical test
- Sets alpha too low
Correct answer: Fails to reject a false null hypothesis
A Type II (beta) error is failing to detect a real effect—accepting a false null hypothesis.
Question 7: Which statistic describes the proportion of variance in the dependent variable explained by the independent variable?
- Cohen's d
- Pearson r
- Coefficient of determination (r²) (Correct answer)
- Standard error
Correct answer: Coefficient of determination (r²)
r² (coefficient of determination) expresses the proportion of variance in Y accounted for by X.
CRC Research Methods 2
A researcher wants to determine whether a new vocational training program causes better employment outcomes compared to no training.
Which research design best supports a causal inference?