ETS Statistical Analysis 4

Question 1

A 95% confidence interval for a population mean is (42, 58). Which interpretation is correct?

Accepted Answer

We are 95% confident the interval (42, 58) captures the true population mean

Answer

There is a 95% probability that the population mean is between 42 and 58

Answer

95% of sample means will fall between 42 and 58

Answer

The sample mean has a 95% chance of being 50

Question 2

Which nonparametric test is the appropriate alternative to the independent samples t-test?

Accepted Answer

Mann-Whitney U test

Answer

Wilcoxon signed-rank test

Answer

Kruskal-Wallis test

Answer

Friedman test

Question 3

In a normal distribution, approximately what percentage of data falls within one standard deviation of the mean?

Accepted Answer

68%

Answer

50%

Answer

95%

Answer

99.7%

Question 4

A researcher uses multiple regression with 4 predictors. The adjusted R² is preferred over R² because it:

Accepted Answer

Penalizes for adding predictors that don't improve the model

Answer

Always equals R² for large samples

Answer

Is always larger than R²

Answer

Eliminates multicollinearity

Question 5

Interquartile range (IQR) is calculated as:

Accepted Answer

Q3 − Q1

Answer

Q2 − Q1

Answer

Q4 − Q1

Answer

Maximum − Minimum

Question 6

When sample size increases, the width of a confidence interval will generally:

Accepted Answer

Decrease

Answer

Increase

Answer

Remain the same

Answer

Double

Question 7

A researcher wants to determine if gender and political preference are related. Which statistical test is most appropriate?

Accepted Answer

Chi-square test of independence

Answer

Independent samples t-test

Answer

One-way ANOVA

Answer

Pearson correlation