5. Statistical Inference

Comparing Groups — Quiz

Test your understanding of comparing groups with 5 practice questions.

Practice Questions

Question 1

What is the correct formula for the standard error of the difference between two independent sample means in the unpooled (Welch’s) two-sample t-test?

Question 2

Which of the following best describes the purpose of checking for normality when comparing two sample means?

Question 3

A researcher is comparing the mean weights of two groups of animals. Group 1 has $n_1 = 20$, $\bar{x}_1 = 15.2$ kg, and $s_1 = 2.1$ kg. Group 2 has $n_2 = 25$, $\bar{x}_2 = 14.8$ kg, and $s_2 = 2.4$ kg. Assuming unequal variances, what is the value of the standard error of the difference in means?

Question 4

Which of the following statements about the pooled two-sample t-test is true?

Question 5

A two-sample z-test for comparing two proportions yields a confidence interval for the difference in proportions as $(-0.12, 0.05)$. What can be concluded from this confidence interval at the 95% confidence level?