NPE Research Methods and Statistics 2 — Questions and Answers
Question 1: Which of the following correlation coefficients reflects the strongest linear relationship between two variables?
- +0.45
- -0.78 (Correct answer)
- +0.62
- -0.31
Correct answer: -0.78
The strength of a correlation is determined by its absolute value; -0.78 has the highest absolute value (0.78) among the options.
Question 2: A researcher rejects the null hypothesis when it is actually true. This is an example of:
- Type II error
- Sampling bias
- Type I error (Correct answer)
- Low statistical power
Correct answer: Type I error
A Type I error (false positive) occurs when the null hypothesis is incorrectly rejected; its probability equals the alpha level.
Question 3: Cohen's d is a commonly reported statistic in psychological research. What does it primarily measure?
- The probability that results occurred by chance
- The practical significance or magnitude of a treatment effect (Correct answer)
- The degree of correlation between two variables
- The proportion of variance explained by a predictor
Correct answer: The practical significance or magnitude of a treatment effect
Cohen's d is an effect size statistic that quantifies the practical magnitude of a difference between means, independent of sample size.
Question 4: A researcher follows the same cohort of children from age 5 to age 18 to study cognitive development. This is best described as a:
- Cross-sectional design
- Case-control design
- Longitudinal design (Correct answer)
- Sequential cohort design
Correct answer: Longitudinal design
A longitudinal design tracks the same participants across extended time periods, allowing researchers to observe developmental changes within individuals.
Question 5: Which measure of central tendency is most resistant to the influence of extreme outliers in a distribution?
- Mean
- Variance
- Median (Correct answer)
- Standard deviation
Correct answer: Median
The median is the middle value and is not affected by extreme scores, making it a more robust measure when outliers are present.
Question 6: Two raters independently score 50 therapy session recordings using the same coding manual. The researcher then calculates intraclass correlation. What is being assessed?
- Test-retest reliability
- Internal consistency
- Inter-rater reliability (Correct answer)
- Predictive validity
Correct answer: Inter-rater reliability
Inter-rater reliability assesses the level of agreement between two or more independent raters using the same measurement instrument.
Question 7: A researcher wants to examine whether there is an association between diagnostic category (MDD, GAD, PTSD) and treatment modality chosen (CBT, DBT, psychodynamic). Which statistical test is most appropriate?
- One-way ANOVA
- Pearson correlation
- Chi-square test of independence (Correct answer)
- Independent samples t-test
Correct answer: Chi-square test of independence
The chi-square test of independence evaluates whether two categorical variables are statistically associated with each other.
NPE Research Methods and Statistics 2
Which of the following correlation coefficients reflects the strongest linear relationship between two variables?