CSP Quantitative Research & Statistics 3 — Questions and Answers
Question 1: Which sampling method involves dividing a population into subgroups and randomly selecting from each subgroup proportionally?
- Cluster sampling
- Systematic sampling
- Stratified random sampling (Correct answer)
- Convenience sampling
Correct answer: Stratified random sampling
Stratified random sampling divides the population into strata (subgroups) and draws random samples from each stratum, ensuring representation of all subgroups.
Question 2: 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
- Selects too small a sample size
Correct answer: Fails to reject a false null hypothesis
A Type II error (false negative) occurs when the null hypothesis is actually false but the researcher fails to reject it, missing a real effect.
Question 3: In regression analysis, multicollinearity refers to:
- Unequal variance across levels of the predictor
- High correlations among independent variables (Correct answer)
- A non-linear relationship between predictor and outcome
- Errors that are not normally distributed
Correct answer: High correlations among independent variables
Multicollinearity occurs when two or more independent variables in a regression model are highly correlated, making it difficult to isolate each variable's unique effect.
Question 4: A z-score of -2.0 indicates that the observation is:
- Two standard deviations below the mean (Correct answer)
- Two standard deviations above the mean
- At the second percentile of a skewed distribution
- Exactly two units from the median
Correct answer: Two standard deviations below the mean
A z-score of -2.0 means the observation lies two standard deviations below the mean of its distribution.
Question 5: Which statistical test is most appropriate to compare the means of three or more independent groups?
- Independent samples t-test
- Paired samples t-test
- One-way ANOVA (Correct answer)
- Mann-Whitney U test
Correct answer: One-way ANOVA
One-way ANOVA (Analysis of Variance) is designed to compare means across three or more independent groups while controlling the overall Type I error rate.
Question 6: A researcher reports that their finding is significant at p < 0.01. This means:
- There is a 1% probability the effect size is large
- There is a 99% probability the null hypothesis is true
- There is less than a 1% probability of obtaining these results if the null hypothesis were true (Correct answer)
- The result will replicate in 99% of future studies
Correct answer: There is less than a 1% probability of obtaining these results if the null hypothesis were true
p < 0.01 means there is less than a 1% probability of observing results as extreme as these if the null hypothesis were actually true.
Question 7: Content validity in a sociological survey instrument refers to:
- The degree to which a measure correlates with an established criterion
- The extent to which items adequately represent all facets of the concept being measured (Correct answer)
- The consistency of scores across repeated administrations
- The factor structure replicating across different samples
Correct answer: The extent to which items adequately represent all facets of the concept being measured
Content validity assesses whether the items in a measure comprehensively cover the full domain of the theoretical concept being studied.
CSP Quantitative Research & Statistics 3
Which sampling method involves dividing a population into subgroups and randomly selecting from each subgroup proportionally?