PubH 6450
NAME:_____________________________________________
Exam 2
(11/11/10)
Lecture Instructor (please circle):
Susan Telke
Andy Mugglin
Directions:
This is an openbook, opennotes exam; however, sharing of books, notes, handouts, homework or lab
papers, calculators, or verbal comments is not permitted.
You may use a calculator of your choosing, but
laptop computers and any kind of internet connection are not permitted.
For multiple choice questions, please clearly indicate your answer(s).
For short answer problems, please show all relevant work necessary to arrive at a solution, as partial
credit will be awarded.
Correct answers without appropriate justification will generally not receive full
credit.
DO NOT LOOK AT OR BEGIN THE EXAM UNTIL
THE INSTRUCTOR ANNOUNCES THAT THE EXAM
IS STARTING.
You will have from 1:25pm to 3:20pm to complete this exam, so do not spend too much time on any
one problem.
With such a big class, there is always someone who needs to take the exam early or late. After the
exam is over,
DO NOT DISCUSS THIS EXAM
with anyone who was not in this same room taking it
with you. We anticipate returning the exams in class on Tuesday.
Advice on rounding:
We suggest that you round calculations (mean, s.d., etc.) to 2 decimal places
(if the data are whole numbers), 3 decimal places (if the data are known to the nearest 0.1), etc.
Probabilities are usually rounded to 3 or 4 decimal places, but no more.
Good luck!!
(1)
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A doctor treating patients with high cholesterol prescribes medicine to lower the patients’
cholesterol. Her patients’ cholesterol levels are measured at each visit. She notices that, in some
of her patients, their cholesterol levels are not changing in subsequent measurements, and she
suspects that this is because these patients are forgetting to take their medication.
She plans to conduct an experiment on a randomly selected sample of 25 patients.
She calls her
patients between the next two visits to remind them to take their medication.
Then she
calculates the mean difference in cholesterol levels between these visits.
Previous studies have
shown that the changes (in measurement between visits) are normally distributed with a standard
deviation of
σ
= 80, so she will proceed with that assumption.
She wants to perform a statistical
test (using α = 0.05) to see if there is statistical evidence of a
change
in cholesterol that might be
attributed to this intervention of calling patients between visits.
a) State the hypotheses (both null and alternative) that she is interested in testing. Be sure to
define any symbols.
b)
In the context of this problem, what is a type I error?
What is the probability that she will
commit one?
c) In the context of this problem, what is a type II error?
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 Fall '10
 AndyMugglin
 Normal Distribution, researcher, Binomial Exact Test, physical function score

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