A researcher conducts an experiment to compare the effectivenessof different therapies for depression. Participants diagnosed withdepression are randomly assigned to one of four groups: Control (notherapy provided), antidepressant medication (SSRI),cognitive-behavioral therapy (CBT), or a combination of medicationand cognitive-behavioral therapy (SSRI+CBT). The DV is depressionseverity after 4 weeks, with higher scores indicating the presenceof more depressive symptoms.
| SSRI | CBT | SSRI+CBT | Control |
| 11 | 7 | 9 | 12 |
| 5 | 9 | 6 | 7 |
| 9 | 6 | 7 | 11 |
| 7 | 11 | 9 | 9 |
| 6 | 7 | 5 | 6 |
| 9 | 6 | 8 | 8 |
| 11 | 9 | 6 | 11 |
| 10 | 8 | 4 | 10 |
| 8 | 7 | 8 | 12 |
| 9 | 9 | 9 | 9 |
Is there a statistically significant difference between thegroups? With ? = .05, perform a oneway between groups ANOVA to findout.
a. Perform the ANOVA in Excel by creating your own formulas andwith the FDIST function to determine p. Create your own fullsummary table.
b. Compute the effect size (eta squared).
c. Create either a bar graph comparing the means of the fourgroups (including standard error bars) or a box-plot displaycomparing the four groups.
d. Insert a textbox reporting your statistical and researchconclusion.
