Started on:
Monday, 25 February 2008, 09:46 PM
Completed on:
Monday, 25 February 2008, 10:42 PM
Time taken:
56 mins 31 secs
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1
Marks: 1
The objective of a study is to find out whether meditation lowers stress level. Thirty six people
volunteer to participate in the study. They meditated for one hour and their stress level was
measured before and after meditaton.
Given the following data what is your decision regarding the null (assume a twotailed
alternative hypothesis)?
d = stress level after meditation minus stress level before meditation
dbar or the mean of stress level after minus before meditation = 12
S(d) or standard deviation of the difference between stress level after and before mediation = 4
N = 36
Choose one answer.
a. Reject the null and conclude that meditation lowers the stress level.
b. Fail to reject the null and coclude that meditation does not lower the stress level.
c. We can reject the null at 95% level of confidence, but, we cannot reject it at 99 level of
confidence.
d. We need the mean and the standard deviation for stress level before and after
meditation to calculate t and decide about H0.
Correct
Marks for this submission: 1/1.
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We showed that for the two sample test of the mean, you calculate t by dividing the difference in
the sample means by
S of (X bar 1 minus Xbar 2)
What does (S of X bar 1 minus Xbar 2) show?
Choose one answer.
a. variance of sample one minus sample two.
b. Standard deviation of the difference between X1 and X2 distribution
c. standard deviation of the difference between two population means
d. standard deviation of (Xbar 1  Xbar 2) distribution
Correct
Marks for this submission: 1/1.
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3
Marks: 1
A statistics professor wants to examine the effect of on line quizzes on students' ability to
interpret confidence intervals.
He randomly assigns his class of 25 students to two groups of 12 and 13. He gives both groups
the same lecture on confidence interval. In addition he has one group take an online quiz about
confidence intervals.
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 Spring '08
 Esfandini
 Statistical hypothesis testing, Andy, Correct Marks

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