Question

A physician at the veterans’ hospital would like to try a new MAOI (monoamine-oxidase inhibitor) drug for his veteran patients diagnosed with PTSD. He wondered if MAOI would affect the frequency of nightmares for this patient population. He first asked 16 of his patients with PTSD to record each incident of a nightmare for 1 month before treatment. Participants were then given the MAOI medication for 6 weeks, and then they were again asked to record each occurrence of a nightmare for a month. The data are listed in the table below. The physician/researcher has set the significance level at ? = .05.

	Number of Nightmares in a Month
Subject	Before MAOI treatment	After MAOI treatment
1	12	8
2	4	6
3	6	5
4	10	10
5	14	10
6	8	8
7	4	6
8	8	6
9	4	2
10	16	7
11	3	3
12	5	4
13	9	8
14	15	7
15	11	13
16	3	5

- What are the “samples” in this paired-samples t test? (Or, what are the “means” in this dependent-means t test?)

-Calculate the raw and standardized effect size of this hypothesis test

The physician could also set up the hypothesis to only test for a beneficial effect of MAOI in reducing the frequency of nightmares. In other words, the research hypothesis could predict a direction of the drug’s effect.

-Was the one-tailed test result (Part II) different from the two-tailed test result (from Part I)? Why or why not?

I know the were different but why?

Answer 1

H0: There is no significance difference between the means of Before and After traterment
H1: There is significance difference between the means of Before and After traterment
Let the los be alpha = 0.05

From the given data

Before	Ater	Difference
12	8	4
4	6	-2
6	5	1
10	10	0
14	10	4
8	8	0
4	6	-2
8	6	2
4	2	2
16	7	9
3	3	0
5	4	1
9	8	1
15	7	8
11	13	-2
3	5	-2

Critical t: ±2.1315
P-Value: 0.0932

Here t value is lies between t critical values and P-value > alpha 0.05 so we accept H0

thus we conclude that there is no significance difference between the means of Before and After traterment

One Tail test:

Critical t: 1.7530
P-Value: 0.0466

Here t value > t critical value and P-value < alpha 0.05 so we reject H0

thus we conclude that treatment is effected