7.1 Learning Objectives

After completing this lab, you should be able to

• Conduct independent samples t tests in R Commander and SPSS
• Interpret the output of an independent samples t test from R Commander and SPSS
• Report the results of an independent samples t test in APA style

Before you begin, make sure you understand the following concepts from the lecture portion of the course

• The goal of an independent samples t test, including what types of research questions it can be used to test
• The concepts behind independent samples t tests
  • t distributions
  • Degrees of freedom
  • Critical t values

This lab will also draw on the following skills learned in earlier labs. You can review previous labs at any time.

• Loading data into R Commander and SPSS. You can review this skill in the videos on R Commander basics (beginning at 3:32) and SPSS basics (beginning at 0:48).
• Producing descriptive statistics in R Commander or SPSS. You can review this skill in the videos on Descriptive statistics in R Commander (beginning at 0:27) and Descriptive statistics in SPSS (beginning at 1:03).

You can download the dataset we will be using in this lab here. In R Commander, you can load the Wells dataset directly from the carData package. For further information about the dataset and variables, refer to the documentation.