BAPSY Methodical & Stats Analysis 3 — Questions and Answers
Question 1: In multiple regression, multicollinearity refers to:
- Correlated residuals across observations
- High correlation among predictor variables (Correct answer)
- Non-linear relationships between predictors and outcome
- Unequal variance across predictor levels
Correct answer: High correlation among predictor variables
Multicollinearity occurs when predictor variables are highly correlated with each other, making it difficult to isolate individual effects.
Question 2: A within-subjects (repeated measures) design reduces error variance primarily by:
- Increasing the number of dependent variables
- Controlling for individual differences across conditions (Correct answer)
- Randomizing condition order across participants
- Eliminating demand characteristics
Correct answer: Controlling for individual differences across conditions
Repeated measures designs use the same participants across conditions, removing between-person variability from the error term.
Question 3: Cronbach's alpha is used to assess:
- Test-retest reliability
- Internal consistency of a scale (Correct answer)
- Inter-rater reliability
- Criterion validity
Correct answer: Internal consistency of a scale
Cronbach's alpha estimates the internal consistency of a multi-item scale by examining inter-item correlations.
Question 4: The p-value in hypothesis testing represents:
- The probability that the null hypothesis is true
- The probability of obtaining results at least as extreme as observed, given H₀ is true (Correct answer)
- The likelihood the alternative hypothesis is correct
- The effect size of the finding
Correct answer: The probability of obtaining results at least as extreme as observed, given H₀ is true
The p-value is the probability of observing data as extreme or more extreme than the sample, assuming the null hypothesis is true.
Question 5: Which of the following is an example of a confounding variable?
- The measured outcome in an experiment
- A manipulated independent variable
- A variable that co-varies with IV and affects DV unintentionally (Correct answer)
- A mediating variable in a causal chain
Correct answer: A variable that co-varies with IV and affects DV unintentionally
A confound is an extraneous variable that varies systematically with the independent variable and influences the dependent variable.
Question 6: Effect size measures such as Cohen's d are important because they:
- Determine statistical significance independent of sample size
- Quantify the practical magnitude of a difference (Correct answer)
- Replace the need for confidence intervals
- Correct for Type I error rate
Correct answer: Quantify the practical magnitude of a difference
Cohen's d expresses the size of a mean difference in standard deviation units, indicating practical significance regardless of sample size.
Question 7: In a 2×3 factorial design, how many main effects are there?
- 1
- 2 (Correct answer)
- 3
- 6
Correct answer: 2
A 2×3 factorial design has two factors, yielding exactly two main effects and one interaction effect.
BAPSY Methodical & Stats Analysis 3
In multiple regression, multicollinearity refers to: