A psychologist is interested in whether hypnosis affects brain dominance. Twelve
ID: 3130376 • Letter: A
Question
A psychologist is interested in whether hypnosis affects brain dominance. Twelve college students from the freshmen class are randomly sampled for an experiment. The experiment has two conditions which are given on different days. In condition 1, the students are hypnotized and then given a test which measures the relative dominance of the right and left hemispheres. The higher the score, the more dominant is the right hemisphere. In condition 2, the same students are given the test again, only this time they are not hypnotized but are in their normal state of consciousness. The following scores are obtained. Student 1 2 3 4 5 6 7 8 9 10 11 12 Condition 1 20 16 22 18 23 30 16 19 14 16 17 25 Condition 2 14 13 17 19 21 22 14 22 12 14 15 22 The obtained probability = _________. ( 10 points) a. 0.0161 c. 0.0192 b. 0.0384 d. 0.0322
Explanation / Answer
Let ud = u2 - u1.
Formulating the null and alternative hypotheses,
Ho: ud = 0
Ha: ud =/ 0
At level of significance = 0.01
As we can see, this is a two tailed test.
Calculating the standard deviation of the differences (third column):
s = 2.906367096
Thus, the standard error of the difference is sD = s/sqrt(n):
sD = 0.838995913
Calculating the mean of the differences (third column):
XD = -2.583333333
As t = [XD - uD]/sD, where uD = the hypothesized difference = 0 , then
t = -3.079077376
As df = n - 1 = 11
Thus, using p values,
p = 0.010488565 [ANSWER]
The closest answer is 0.0161 [OPTION A]. However, I think there is a typo error in the data.
If not, please report this problem to your instructor. Thanks!
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