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. Light Intensity Low Medium High Time of Day Morning 5 5 7 6 6 8 3 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 (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.) Source of Variation SS df MS F Time of day Intensity Time of day × Intensity Error Total 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.
Answer to the question)
enter the data in excel
click on the data tab
click on data analysis
Select ANOVA two factor , with replication
click ok
the following window appears on screen
.
enter the data range
rows per sample = 6
click ok
we get the following output
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