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 do the following:

• 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.