Independent Samples t-Test

Intro Statistics for Social Sciences (Professor April Garcia Peck)

Prepare: Watch the jamovi video lessons for Lesson 10. 

Dataset needed: jamovi Dataset - Lesson 10.omv

Assignment Prompt:

A psychologist was tasked with evaluating a new Group Therapy Program for a clinic that serves over 500 clients every year. The psychologist recruited 22 people with a diagnosis of Major Depressive Disorder. These individuals were already seeing a therapist on a weekly basis. The volunteers agreed to try the new Group Therapy Program in addition to their ongoing individual therapy sessions. Eleven of the volunteers attended the 8-week group therapy sessions and the other 11 volunteers were assigned to the Waitlisted Control condition in which they were waitlisted for the group therapy program. The psychologist asked the clients to report the number of daily living activities (DLAs) they performed each day. Daily living activities include bathing, dressing, meal preparation, going to work, exercising, etc. Was the Group Therapy Program successful in increasing rates of daily living activities? Test this hypothesis using alpha levels of .01 and .05 (you will compare p to both alphas). 

Use jamovi to find the answers to the items below:

1. What is t-obtained? Report to 2 decimal places AND include the sign whether it is negative (-) or positive (+). ______

2. What is the mean DLA for the Therapy Group? (report to 2 decimal places) ______

3. What is the mean DLA for the Waitlisted Control Group? (report to 2 decimal places) ______

4. What is the p-value? (report to 3 decimal places) ______

5. What is your decision regarding H0 if alpha is .01? (Remember, your conclusion should be 3 statements.)

6. What is your decision regarding H0 if alpha is .05? (Remember, your conclusion should be 3 statements.)