Download Biometry Assignment #5 ~ CI`s and Hypothesis Testing

Biometry Assignment #5 ~ Applications of Sampling
Distributions: CI’s and Decision Making (Due 2/25/11)
1. In a random sample of 1215 animals, 362 exhibited a certain trait defect. Determine the
95% confidence interval for the proportion of the population displaying the trait. Also
give the correct interpretation of this interval. (5 pts.)
2. A severe drought in 1987 affected both the death rate of seedlings and the growth rate
of established trees. It is thought that a majority of the trees in the affected areas have a
1987 growth ring that is less than one half the size of the trees' other growth rings. A
sample of 250 trees yielded 150 with this characteristic. Do these data support the claim
that a majority of trees exhibited the growth defect? (5 pts.)
3. A topic of recent clinical interest is the possibility of using drugs to reduce the infarct
size in patients who have had a myocardial infarction within the past 24 hours. Suppose
we know that in untreated patients the mean infarct size is 25 (ck-g-EQ/m2). In a study of
25 patients treated with a drug the mean infarct size is 16 (ck-g-EQ/m2) with a standard
deviation of 12.5. Do these results provide “statistically significant” evidence that the
drug is effective in reducing infarct size? Show all your work and justify your answer.
(5 pts.)
4. Renal Blockage
A study is run to determine the effects of removing a renal blockage in patients whose
renal function is impaired because of advanced metastatic malignancy of nonurologic
cause. The arterial blood pressure in each patient is measured before (X) and after (Y)
surgery. The results are in the table below.
Patient Before (X) After (Y) Difference (X – Y)
1
150
90
2
132
102
3
130
80
You will probably want to
4
116
82
enter these differences into
5
107
90
JMP and use Distribution to
6
100
94
obtain the necessary summary
7
101
84
statistics.
8
96
93
9
90
89
10
78
85
Find a 95% CI for the mean change in the arterial blood pressure of this population of
patients after having undergone surgery. Interpret this interval. Does this suggest that
the arterial blood pressure of these patients on average decreases after surgery? Explain.
(5 pts.)