QUESTION 5 11 F It is now known that exposure to bright light can help patients

Question

QUESTION 5 11 F It is now known that exposure to bright light can help patients with winter depression. In an early study of the effect of bright light in 1987, eight patients with winter depression were randomly assigned to bright light in the morning or bright light in the evening for one week The second week, each patient was exposed to bright light in the opposite time period. Before the trial, and after each week of light exposure, their depression was measured using the Hamilton Depression Rating. Here are some of the the results: subject baseline score morning light difference 21 13 3 23 4 10 16 10 712 25 4 17

Explanation / Answer

R codes :

> baseline=c(21,13,23,10,9,10,12,25)
> morning=c(9,6,16,3,1,3,4,17)
> t.test(baseline,morning,paired=T)

Paired t-test

data: baseline and morning
t = 13.387, df = 7, p-value = 3.043e-06
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
6.586867 9.413133
sample estimates:
mean of the differences
8

c) Since p-value is very small, we reject the null hypothesis of no significance and conclude that there is significant reduction in depression rating score after exposure to morning light."Statistically significant" means that the reduction is not due to chance causes but are real.

d) 95% C.I : ( 6.586867,9.413133 )

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