STAT 205 Name:
____ANSWER KEY
___
Fall 2007
Exam 2
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View Full DocumentPart I: Answer eight of the following nine questions. If you complete more than eight, I will
grade only the first eight. Five points each.
1) State the definition of a Pvalue.
The Pvalue of a test is the probability under H
0
, of observing a test statistic as extreme or
more in the direction of HA as that actually observed.
2)
For a 95% confidence interval for the population mean,
μ
, how is the length of the interval related
to margin of error?
The length of the interval is 2 x MOE.
3)
A certain drug causes drowsiness in 20% of patients. Suppose the drug is to be given to 5
randomly chosen patients. Let
p
ො
represent the proportion of patients in the sample who experience
drowsiness. Find Pr{
p
ො
≤
1}.
Pr{
p
ො
≤
1} = Pr{
p
ො
=0/5}+Pr{
p
ො
=1/5}+Pr{
p
ො
=2/5}+Pr{
p
ො
=3/5}+Pr{
p
ො
=4/5}+Pr{
p
ො
=5/5} = 1 since we’re
summing over the probabilities of all events in the sample space
4)
(Circle the correct answer) A study of the effect of transdermal estradiol on postmenopausal
women was conducted. Plasma levels of plasminogenactivator inhibitor type 1 (PA1) were
measured for 20 women before and after being administered transdermal estradiol. We would use the
independent / dependent (paired)
samples method in order to conduct a test of hypothesis for the
difference between the mean PA1 levels of these two populations.
5)
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 Fall '09
 Hendrix
 Nitric oxide, Statistical hypothesis testing

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