Seasonal affective disorder (SAD) is a type of depression during seasons with le
ID: 3181359 • 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. Light Intensity Low Medium High Time of Day Morning 5 5 7 5 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 2 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.) 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 5 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 2 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.) 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 5 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 2 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.)Explanation / Answer
Answer:
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 5 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 2 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.)
Two factor ANOVA
Light Intensity
Means:
Low
Medium
High
Morning
5.3
6.5
7.2
6.3
Time
Night
5.3
7.2
7.2
6.6
5.3
6.8
7.2
6.4
6
replications per cell
ANOVA table
Source
SS
df
MS
F
p-value
Time
0.44
1
0.444
0.18
.6756
Light Intensity
22.89
2
11.444
4.60
.0181
Interaction
0.89
2
0.444
0.18
.8373
Error
74.67
30
2.489
Total
98.89
35
To test main effect Time,
Calculated F=0.158, P=0.6756 which is > 0.05 level. Ho is not Rejected.
We conclude that there is no mean difference between morning and night
To test main effect Light Intensity,
Calculated F=4.60, P=0.0181 which is < 0.05 level. Ho is Rejected.
We conclude that there is mean difference between three Light Intensities.
To test interaction effect,
Calculated F=0.18, P=0.8373 which is > 0.05 level. Ho is not Rejected.
We conclude that interaction effect is not significant.
Two factor ANOVA
Light Intensity
Means:
Low
Medium
High
Morning
5.3
6.5
7.2
6.3
Time
Night
5.3
7.2
7.2
6.6
5.3
6.8
7.2
6.4
6
replications per cell
ANOVA table
Source
SS
df
MS
F
p-value
Time
0.44
1
0.444
0.18
.6756
Light Intensity
22.89
2
11.444
4.60
.0181
Interaction
0.89
2
0.444
0.18
.8373
Error
74.67
30
2.489
Total
98.89
35
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