BAPSY Psychological Research and Statistics 4 — Questions and Answers
Question 1: Which coefficient is most appropriate for assessing inter-rater reliability when both raters use nominal categories?
- Pearson r
- Cronbach's alpha
- Cohen's kappa (Correct answer)
- Spearman's rho
Correct answer: Cohen's kappa
Cohen's kappa corrects for chance agreement between raters on categorical data, making it the standard for nominal inter-rater reliability.
Question 2: In multiple regression, multicollinearity is a problem because it:
- Reduces the overall R² of the model
- Makes it difficult to separate the unique contributions of correlated predictors (Correct answer)
- Violates the assumption of normality of residuals
- Increases the effect size of each predictor
Correct answer: Makes it difficult to separate the unique contributions of correlated predictors
High multicollinearity inflates standard errors of regression coefficients, making it hard to determine each predictor's unique contribution.
Question 3: The distinction between a population parameter and a sample statistic is that:
- Parameters are always larger than statistics
- Parameters describe populations; statistics describe samples and estimate parameters (Correct answer)
- Statistics are fixed values; parameters change across studies
- Parameters can only be calculated with census data
Correct answer: Parameters describe populations; statistics describe samples and estimate parameters
Parameters (e.g., μ, σ) are fixed but usually unknown values describing a population; statistics (e.g., x̄, s) are calculated from samples to estimate them.
Question 4: A meta-analysis synthesizes findings across studies primarily to:
- Repeat the best individual study with a larger sample
- Qualitatively summarize the narrative of a field
- Quantitatively estimate the average effect size across multiple studies (Correct answer)
- Replace systematic reviews in evidence-based practice
Correct answer: Quantitatively estimate the average effect size across multiple studies
Meta-analysis uses statistical procedures to combine effect sizes from multiple studies, yielding a more precise overall estimate of an effect.
Question 5: An operational definition in research serves to:
- State the theoretical meaning of a construct
- Specify exactly how a variable is measured or manipulated in a study (Correct answer)
- Identify the population to which results generalize
- Describe the ethical protections offered to participants
Correct answer: Specify exactly how a variable is measured or manipulated in a study
Operational definitions translate abstract constructs into concrete, measurable procedures, enabling replication and clarity.
Question 6: Which of the following best describes the concept of regression to the mean?
- Scores naturally drift toward the population mean over repeated measurements
- The regression line always passes through the origin
- Extreme scores on a first measurement tend to be less extreme on a second measurement (Correct answer)
- The mean decreases as sample size increases
Correct answer: Extreme scores on a first measurement tend to be less extreme on a second measurement
Regression to the mean describes the statistical tendency for extreme first-time scores to be closer to the average upon retesting, due to random error.
Question 7: In a chi-square test of independence, a significant result indicates that:
- There is a causal relationship between the two categorical variables
- The observed frequencies differ significantly from expected frequencies under independence (Correct answer)
- The two variables are perfectly correlated
- The sample size was too small to detect an effect
Correct answer: The observed frequencies differ significantly from expected frequencies under independence
A significant chi-square means the pattern of observed cell frequencies is unlikely to occur if the two categorical variables were truly independent.
BAPSY Psychological Research and Statistics 4
Which coefficient is most appropriate for assessing inter-rater reliability when both raters use nominal categories?