4.3 Analysis

Remember, this data set is available from the textbook as forwardfall.csv in Appendix A. You can download the data and follow along if you wish.

Use the jamovi menu: select Analyses> T-Tests> Independent Samples T-Test
Select the Variables.
- For the Dependent Variables, add the quantitative variable (here, LeanAngle).
- For the Grouping Variable, add the qualitative variable (here, Group).
Then select the options:

Student's and Welch's should be select to perform the hypothesis test and compute the CIs.
Mean difference to show the difference between the two means in the output.
Confidence interval to show the CI for the difference between the two means.
Descriptives to show the numerical summary of each group.
Descriptives plot to show the error bar chart.

Even if you have a one-tailed hypothesis, keep the hypotheses as the two-tailed (first) option, or you will get some strange output. The one-tailed \(P\)-value will be half the two-tailed \(P\)-value.

FIGURE 4.4: Enter the variables

You will have your output in the jamovi Output window.