7.1 Learning Objectives

After completing this lab, you should be able to do the following using R:

  • Conduct both Student’s and Welch’s independent samples t tests.
  • Compute Cohen’s d by conversion from the test statistic using psych::t2d().
  • Create appropriate visualizations for comparisons of two independent samples (as described in the assignment instructions).
  • Produce a single figure with subplots for each level of a grouping variable using ggplot2::facet_wrap().
  • Calculate group-level descriptive statistics using by() and describe().

Additionally, you should be able to:

  • Evaluate the assumptions of independent samples t tests.
  • Explain the difference between Student’s t tests and Welch’s t tests.
  • Accurately interpret the results of independent samples t tests.
  • Report the results of independent samples t tests in APA style.