CRS Statistical Analysis & Software 2 — Questions and Answers
Question 1: In SPSS, which procedure is used to test whether the means of three or more independent groups differ significantly?
- Paired Samples T-Test
- One-Way ANOVA (Correct answer)
- Bivariate Correlation
- Linear Regression
Correct answer: One-Way ANOVA
One-Way ANOVA (Analyze > Compare Means > One-Way ANOVA) tests for significant mean differences across three or more independent groups.
Question 2: What does a Cronbach's alpha value of 0.85 indicate about a research scale?
- The scale has poor internal consistency
- The scale has acceptable internal consistency
- The scale has high internal consistency (Correct answer)
- The scale is unidimensional
Correct answer: The scale has high internal consistency
A Cronbach's alpha of 0.85 indicates high internal consistency, meaning items on the scale are strongly correlated with each other.
Question 3: When conducting a chi-square test of independence, what is the minimum expected cell frequency recommended to ensure test validity?
- 1
- 3
- 5 (Correct answer)
- 10
Correct answer: 5
The standard rule requires expected cell frequencies of at least 5 in each cell to ensure the chi-square approximation is valid.
Question 4: In R, which function is used to create a linear regression model?
- glm()
- lm() (Correct answer)
- aov()
- cor()
Correct answer: lm()
The lm() function in R fits linear models, returning coefficients, residuals, and model fit statistics.
Question 5: What statistical concept does the term 'heteroscedasticity' refer to in regression analysis?
- Multicollinearity among predictors
- Non-normality of the dependent variable
- Non-constant variance of residuals across fitted values (Correct answer)
- Autocorrelation of observations
Correct answer: Non-constant variance of residuals across fitted values
Heteroscedasticity occurs when the variance of regression residuals is not constant across all levels of the independent variable.
Question 6: Which SAS procedure is primarily used for logistic regression analysis?
- PROC REG
- PROC GLM
- PROC LOGISTIC (Correct answer)
- PROC FREQ
Correct answer: PROC LOGISTIC
PROC LOGISTIC in SAS fits logistic regression models for binary, ordinal, or nominal outcome variables.
Question 7: A researcher finds a statistically significant result with p = 0.03 but a Cohen's d of 0.12. What does this most likely indicate?
- A large and meaningful effect
- A statistically significant but practically small effect (Correct answer)
- A Type I error has occurred
- The study should be replicated immediately
Correct answer: A statistically significant but practically small effect
A small Cohen's d (below 0.2) indicates a trivial effect size, meaning the significant p-value is likely driven by a large sample rather than a meaningful difference.
CRS Statistical Analysis & Software 2
In SPSS, which procedure is used to test whether the means of three or more independent groups differ significantly?