EBK BUSINESS STATISTICS
7th Edition
ISBN: 8220102743984
Author: STEPHAN
Publisher: PEARSON
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An experimenter wants to study the relationship between type of milk and infant growth in underdeveloped countries. She randomly assigns 300 infants to either a breast-feeding group or an infant formula group. She then weighs the infants every three days for the first four weeks of life.
A team of UMD students have invented an inhalable drug that
they think will help people breathe better during hard exercise.
They test the drug on 3 volunteers (A, B, and C) by measuring
their levels of arterial oxygen before receiving the drug (their
base level) and then after 5 and 10 minutes have elapsed,
respectively. The results are listed in the table.
Oxygen level [mmHg] A B C
base level
847076
after 5 minutes
85 74 81
after 10 minutes
90 75 98
We want to see how the drug work (better or worse) when
compared to the base level. Compute the 90% two-sided
confidence intervals for the mean difference between the base
level and after 5 minutes.
X1b
Xub
X 1b
-5.1783
Xub
11.8450
Compute the 90% two-sided confidence intervals for the mean
difference between the base level and after 10 minutes.
-1.94
? Xx 0%
23.94
? × 0%
? × 0%
X 0%
CD4 cells are carried in the blood as part of the human immune system. One of the effects of the HIV virus is that these cells die. In this study of the effectiveness of a new anti-viral drug on HIV, 20 HIV-positive patients had their CD4 counts recorded (“Baseline”) and then were put on a course of treatment with this drug. After using the drug for one year, their CD4 counts were again recorded (“OneYear”). The aim was to show that patients taking the drug had increased CD4 counts which is not generally seen in HIV-positive patients.
Baseline
OneYear
2.12
2.47
4.35
4.61
3.39
5.26
2.51
3.02
4.04
6.36
5.1
5.93
3.77
3.93
3.35
4.09
4.1
4.88
3.35
3.81
4.15
4.74
3.56
3.29
3.39
5.55
1.88
2.82
2.56
4.23
2.96
3.23
2.49
2.56
3.03
4.31
2.66
4.37
3.00
2.40
1) What is the correlation between baseline and one year CD4 counts?
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