Seasonal affective disorder (SAD) is a type of depression during seasons with le
ID: 3056566 • 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 7 4 9 7 3 8 6
Explanation / Answer
when p-value < 0.05
we reject the null hypothesis
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 With Replication SUMMARY Total 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 Count 6 6 6 18 Sum 33 43 42 118 Average 5.5 7.166666667 7 6.555555556 Variance 3.5 2.166666667 1.2 2.614379085 Total Count 12 12 12 Sum 66 82 85 Average 5.5 6.833333333 7.083333333 Variance 2.090909091 2.696969697 1.537878788 ANOVA Source of Variation SS df MS F P-value F crit Sample 0.25 1 0.25 0.11002445 0.742422509 4.170876786 Columns 17.38888889 2 8.694444444 3.826405868 0.033102259 3.315829501 Interaction 1.166666667 2 0.583333333 0.256723716 0.775264077 3.315829501 Within 68.16666667 30 2.272222222 Total 86.97222222 35Related Questions
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