STATISTICS 101 - Homework 5
Due Friday, March 1, 2002
• Homework is due by 5:00 PM on the due date at your course instructor’s office. You can always hand
in your homework at the end of lecture.
• You may talk with others about the homework problems but please write your solutions up independently.
• Please answer homework questions in complete sentences. Make sure to
assignment together. Be sure to indicate your lab section on
staple the pages of your
your paper.
• You will have an opportunity to get help on homework during lab.
Reading:
Feb. 11
Feb. 20
Feb. 22
- Feb. 18
- Feb. 27
Sections 3.1, 3.2
Section 4.1
Section 1.3
Assignment:
1. Read pages 164-181 and answer exercises 3.2, 3.6 and 3.10 in the text.
2. Read pages 186-200 and answer exercises 3.32, 3.38 and 3.48 in the text.
3. The article below is excerpted verbatim from a USA TODAY story by Earle Eldridge and Sara Nathan
that appeared on August 14, 2000.
Data point to Firestone tires made at Illinois factory
Five days after Bridgestone/Firestone voluntarily recalled at least 6.5 million tires, its biggest
customer has released new details showing why one tire size – and one plant’s output – are
under scrutiny.
Ford Motor’s analysis of Firestone customers’ complaints about the Firestone tires – many
installed as original equipment on Ford sport-utility vehicles and pickups – provided the basis
for Firestone’s decision to voluntarily recall Wilderness AT tires made in Decatur, Ill., and
ATX and ATX II tires. Only P235/75R-15 tires in the three lines are affected. The analysis
shows:
• Of 2,504 customer claims under Firestone tire warranties over the past nine years, 2,030,
or 81%, involved P235/75R-15 tires.
• Tread-separation complaints for the P235/75R-15 Wilderness tires are highest by far for
those made in Decatur in 1996. Firestone received 10 times more complaints about the
tires made in Decatur that year than it did for the same size and model made at all
other plants.
The complaint rate fell by half for tires made there in 1997 and much lower the next two years.
“These numbers clearly point to Decatur,”says Ford spokesman Jason Vines.
(a) Is this study an experiment? Explain briefly.
(b) What is(are) the response variable(s)? What is(are) the explanatory variable(s)?
(c) What information backs Ford’s claims that only P235/75R-15 tires are affected and that the
Decatur, Ill. plant is the problem.
1
4. The article below is excerpted verbatim from a USA TODAY story by Donna Leinwand that appeared
on August 14, 2000.
Study: Acupuncture cuts cocaine cravings
The ancient Chinese therapy of acupuncture can help cocaine addicts control their cravings
when it is combined with more modern treatments, says a new study in the Archives of
Internal Medicine.
In the study of 82 addicts, one group received eight weeks of treatment in which an acupuncturist inserted needles into four specific points on the outer ear where stimulation is believed
to have a therapeutic effect. Another group received acupuncture to points on the ear that
are not thought to have any treatment effect. A control group watched relaxation videos.
Slightly more than half the addicts who received the specific acupuncture tested free of cocaine in the last week of treatment, compared with 23.5% of the other acupuncture group
and 9% of the group that watched the tape.
Participants were addicted to cocaine and heroin. In addition to the acupuncture, they
received counseling and methadone for heroin addiction. About a third of those enrolled in
the study dropped out before completing treatment.
(a) Is this study an experiment? Explain briefly.
(b) What is the response variable?
(c) What is the explanatory variable?
(d) What treatments are compared?
(e) What important information about the design of the study appears in the article?
(f) Is any important information omitted? If so, what?
(g) Based on a combination of the information in the article and your knowledge of sound study
design, make an outline that shows how you think the study was designed. Hint: Look at pages
190-191 in the text
R.
5. The following is excerpted verbatim from a package of COLD-EEZE
R
CLINICALLY PROVEN COLD-EEZE
WITH ZIGGT M
R with ZiggT M (Zinc Gluconate Glycine),
The following studies apply only to Cold-Eeze
the only great tasting lozenge proven effective in treating a Common Cold.
A randomized, double-blind placebo study, with 23mg of ionic zinc in a citrus flavored
lozenge, concluded that treatment of a cold with our Patented formula within 48 hours of
the onset resulted in symptom relief and a 42% reduction in the duration of the common
cold.
(a) What is a “randomized, double-blind placebo study”?
(b) What important piece of information is missing from the description of the study?
R study.
(c) Construct a diagram, like the one on pages 190-191 in your text depicting the Cold-Eeze
(d) What does the phrase “Resulted in a 42% reduction in the duration of common cold symptoms.”
mean?
2