Seasonal affective disorder (SAD) is a type of depression during seasons with le

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 Light Intensity Low Medium High Morning 6 4 5 9 5 7 Time of Day Night 6 7 9 (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.)

Explanation / Answer

applying two way ANOVA on above:

SUMMARY low medium High Total morning Count 6 6 6 18 Sum 32 39 42 113 Average 5.3333333 6.5 7 6.277778 Variance 1.0666667 3.5 2 2.447712 Night Count 6 6 6 18 Sum 32 43 42 117 Average 5.3333333 7.166667 7 6.5 Variance 4.2666667 2.166667 1.6 3.088235 Total Count 12 12 12 Sum 64 82 84 Average 5.3333333 6.833333 7 Variance 2.4242424 2.69697 1.6363636 ANOVA Source of Variation SS df MS F P-value F crit time of day 0.44 1 0.44 0.18 0.67 4.17 intensity 20.22 2 10.11 4.16 0.03 3.32 time of day*intensity 0.89 2 0.44 0.18 0.83 3.32 Error 73.00 30 2.43 Total 94.56 35

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.