Use the preparation materials to prepare hand-written answers for the following questions. Please ask any questions on the "Questions -- Preparation Guide" on the course Team (see link on the homepage.)
  1. What type of response variable is used in a 2-sample t-test?
  2. What type of explanatory variable is used in a 2-sample t-test?
  3. What are the null and alternative hypotheses in a 2-sample t-test?
  4. What are the three assumptions of a 2-sample t-test?
  5. What test is used to test that population variances are equal?
  6. What is the formula for the combined sample variance (across both groups)?
  7. What is the statistic for a 2-sample t-test?
  8. What is the test statistic (i.e., the formula) for a 2-sample t-test?
  9. What are the degrees-of-freedom for that test statistic?
  10. Describe in words what the numerator in the test statistic represents.
  11. Describe in words what the denominator in the test statistic represents.
  12. What do you conclude if the p-value<α in a 2-sample t-test?
  13. What do you conclude if the p-value<α in a Levene’s test?
  14. In the signal-to-noise metaphor, what would a plot with low “signal” and low “noise” look like?
  15. In the signal-to-noise metaphor, what would a plot with high “signal” and low “noise” look like?
  16. What do you expect for the p-value of a 2-sample t-test to be if the signal-to-noise ratio is very small (i.e., much more noise than signal)?