Seasonal affective disorder (SAD) is a type of depression during seasons with le
ID: 3055008 • Letter: S
Question
Seasonal affective disorder (SAD) is a type of depression during seasons with less daylight (e.g., winter months). One therapy for SAD is phototherapy, which is increased exposure to light used to improve mood. A researcher tests this therapy by exposing a sample of SAD patients to different intensities of light (low, medium, high) in a light box, either in the morning or at night (these are the times thought to be most effective for light therapy). All participants rated their mood following this therapy on a scale from 1 (poor mood) to 9 (improved mood). The hypothetical results are given in the following table.
(a) Complete the F-table and make a decision to retain or reject the null hypothesis for each hypothesis test. (Round your answers to two decimal places. Assume experimentwise alpha equal to 0.05.)
State the decision for the main effect of the time of day.
Retain the null hypothesis.Reject the null hypothesis.
State the decision for the main effect of intensity.
Retain the null hypothesis.Reject the null hypothesis.
State the decision for the interaction effect.
Retain the null hypothesis.Reject the null hypothesis.
(b) Compute Tukey's HSD to analyze the significant main effect.
The critical value is for each pairwise comparison.
Summarize the results for this test using APA format.
Day Morning 5 5 7 6 6 8 4 4 6 7 7 9 5 9 5 6 8 8 Night 5 6 9 8 8 7 6 7 6 7 5 8 4 9 7 3 8 6
Explanation / Answer
if p-value < 0.05
we reject the null hypothesis
hence
State the decision for the main effect of the time of day.
Retain the null hypothesis
State the decision for the main effect of intensity.
Reject the null hypothesis.
State the decision for the interaction effect.
Retain the null hypothesis
Anova: Two-Factor Wit+A27+A1:C31+A1:C+A1:G30 SUMMARY Low Medium High Total morning Count 6 6 6 18 Sum 33 39 43 115 Average 5.5 6.5 7.166666667 6.388888889 Variance 1.1 3.5 2.166666667 2.486928105 night Count 6 6 6 18 Sum 33 43 43 119 Average 5.5 7.166666667 7.166666667 6.611111111 Variance 3.5 2.166666667 1.366666667 2.722222222 Total Count 12 12 12 Sum 66 82 86 Average 5.5 6.833333333 7.166666667 Variance 2.090909091 2.696969697 1.606060606 ANOVA Source of Variation SS df MS F P-value F crit time of day 0.444444444 1 0.444444444 0.193236715 0.663386732 4.170876786 intensity 18.66666667 2 9.333333333 4.057971014 0.027556176 3.315829501 time of day*intensity 0.888888889 2 0.444444444 0.193236715 0.825304705 3.315829501 Within 69 30 2.3 Total 89 35Related Questions
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