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Question 1
The following data were collected in a clinical trial to compare a new drug to a placebo for its
effectiveness in a lowering total serum cholesterol. Generate a 95% confidence interval for the
difference in mean total cholesterol levels between treatments.
New Drug (n=75)
Placebo (n=75)
Total sample (n=150)
Men (SD) Total
Serum Cholesterol
185.0 (24.5)
204.3 (21.8)
194.7 (23.2)
% patients with Total
Cholesterol < 200
78.0%
65.0%
71.5%
A. Upper limit
-11.88
B. Lower limit
-26.72
C. Based on the confidence interval which of the following is (are) true? (a)
There is significant
evidence, alpha = 0.05, to show that there is a difference in total serum cholesterol between
treatments New Drug and Placebo
(b) There is not significant evidence, alpha = 0.05, to show
that there is a difference in total serum cholesterol between treatments New Drug and Placebo (c)
The difference between total cholesterol between treatments New Drug and Placebo is
essentially 0 (d) b and c.

Question 2
A study is designed to investigate whether there is a difference in response to various treatments
in patients with rheumatoid arthritis. The outcome is patient’s self-reported effect of treatment.
The dada are shown below. Are symptoms independent of treatment? Conduct a ChiSquare test
at a 5% level of significance.
Symptoms
Worsened
No Effect
Symptoms
Improved
Total
Treatment 1
22
14
14
50
Treatment 2
14
15
21
50
Treatment 3
9
12
29
50
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2
Based on comparing the computed statistics to the critical value which of the following is (are)
true? (a)
There is significant evidence, alpha = 0.05, to show that treatment and response are not
independent
(b) there is not significant evidence, alpha = 0.05, to show that treatment and
response are not independent (c) there is significant evidence, alpha = 0.05, to show that
treatment and response are independent (d) b and c