In an effort to determine the effectiveness of light therapy to alleviate depression, you recruit a group of individuals who have been diagnosed with depression. The participants are randomly assigned to one of three groups: Group 1 will be the control group—members of this group will receive no light therapy. Members of Group 2 will get light therapy for 1 hour on even-numbered days over the course of 1 month. Members of Group 3 will get light therapy every day for 1 hour over the course of 1 month. After 1 month, all participants will complete the Acme Mood Scale, consisting of 10 questions; this instrument renders a score between 1 and 100 (1 = Extremely bad mood . . . 100 = Extremely good mood). Each participant’s age will also be recorded (as the covariate).
Data set: Ch 06 – Exercise 04A.sav

Codebook
Variable: Group
Definition: Group number
Type: Categorical (1 = No light therapy, 2 = Light therapy: even days, 3 = Light therapy: every day)
Variable: Mood
Definition: Acme Mood Scale
Type: Continuous (1 = Extremely bad mood . . . 100 = Extremely good mood)
Variable: Age
Definition: Age
Type: Continuous
a. Write the hypotheses.
b. Run each criterion of the pretest checklist (homogeneity of regression slopes, homogeneity of variance [Levene’s test]) and discuss your findings.
c. Run the ANCOVA test and document your findings (ns, means, and Sig. [p value], hypotheses resolution).
4. Write an abstract under 200 words detailing a summary of the study, the ANCOVA test results, hypothesis resolution, and implications of your findings.