Biometry Assignment #1 (29 Points - Due Friday, January 24th)
1. An aquatic biologist would like to take n = 25 random rake samples of the aquatic
vegetation growing in the portion of Lake Winona shown below.
How would you recommend this be done? Use the diagram above in explaining your
sampling plan. (4 pts.)
2. Which technique for gathering data (observational study or experiment) do
you think was used in the following studies? Explain. (2 pts. each)
(a) The Colorado Division of Wildlife netted and released 774 fish at Quincy
Reservoir. There were 219 perch, 315 bluegill, 83 pike, and 157 rainbow trout.
(b) The Colorado Division of Wildlife caught 41 bighorn sheep on Mt. Evans
and gave each one an injection to prevent heartworm. A year later, 38 of
these sheep did not have heartworm, while the other three did.
(c) The Colorado Division of Wildlife imposed special fishing regulations on the
Deckers section of the South Platte River. All trout under 15 inches had to be
released. A study of trout before and after the regulation went into effect
showed that the average length of a trout increased by 4.2 inches after the
new regulation.
(d) An ecology class used binoculars to watch 23 turtles at Lowell Ponds. It was
found that 18 were box turtles and 5 were snapping turtles.
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3. An agricultural study is comparing the harvest volume of two types of barley.
The site for the experiment is bordered by a river. The field is divided into eight
plots of approximately the same size. The experiment calls for the plots to be
blocked into four plots per block. Then, two plots of each block will be randomly
assigned to one of the two barley types. Two blocking schemes are shown
below, with one block indicated by the white region and the other by the gray
region. Which blocking scheme, A or B, would be better? Explain. (3 pts.)
4. How would you use a completely randomized experiment in each of the
following settings? Is a placebo being used or not? Be specific and give details.
(3 pts. each)
(a) A veterinarian wants to test a strain of antibiotic on calves to determine their
resistance to common infection. In a pasture are 22 newborn calves. There is
enough vaccine for 10 calves. However, blood tests to determine resistance
to infection can be done on all calves.
(b) A skin patch contains a new drug to help people quit smoking. A group of
75 cigarette smokers have volunteered as subjects to test the new skin patch.
For one month, 40 of the volunteers receive skin patches with the new drug.
The other volunteers receive skin patches with no drugs. At the end of two
months, each subject is surveyed regarding his or her current smoking habits.
5. Thinking ahead…
Suppose we wish to determine if the typical mercury level found in the tissues of
walleyes in Lake Pepin exceeds .25 parts per million (ppm). To help make this
determination suppose we randomly sample n = 200 walleyes and find that the
average mercury level found in these fish is .33 ppm. Can we conclude that the
typical mercury level exceeds .25 ppm on the basis of this result? Give your
answer and carefully explain your reasoning. Note: You can assume this
sampling was done “perfectly”, in other words your reasoning should not be
attacking the sampling scheme used. (4 pts.)
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6. Does the study discussed below prove that heavy coffee drinking causes
increased chance of death in adults under 55 years of age? Discuss some
plausible reasons why researchers would see this increased risk of death
associated with heavy coffee consumption. (4 pts.)
Heavy coffee consumption linked to
higher death risk
Cathy Payne, USA TODAY8:30 a.m. EDT August 16, 2013
Drinking more than 28 cups of coffee a week may be harmful
for people younger than 55, according to a study.
http://www.usatoday.com/story/news/nation/2013/08/15/coffee-consumptiondeath-risk/2655855/
(Photo: Todd Plitt, USA TODAY)
STORY HIGHLIGHTS


Caffeine is a stimulant with potential adverse effects
Coffee is a source of antioxidants

Studies about coffee have yielded mixed results
The debate over coffee's health risks continues to brew. A new study, out
Thursday, finds that heavy coffee consumption is associated with a higher death
risk in men and women younger than 55.
In the study published online in the journal Mayo Clinic Proceedings, men
younger than 55 who drank more than 28 cups of coffee a week (four cups a day)
were 56% more likely to have died from any cause. Women in that age range had
a twofold greater risk of dying than other women. The study looked at 43,727
men and women ages 20-87 from 1971 to 2002.
"From our study, it seems safe to drink one to three cups of coffee a day," says
the study's second co-author Xuemei Sui. "Drinking more than four cups of coffee
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a day may endanger health," says Sui, assistant professor of exercise science
with theArnold School of Public Health at the University of South Carolina in
Columbia. She defines a cup of coffee as 6 to 8 ounces.
The study did not find a higher death risk for adults 55 and older. Sui says there
may be a bias — the research may not include unhealthy older people because
they might have already died.
The reasons for the higher death risk among younger adults are not clear since
experts through the years have found both health benefits and problems
associated with coffee.
Sui says the caffeine in coffee can elevate heart rate as well as raise blood
pressure and blood sugar levels. However, coffee is a major source of
antioxidants, she says.
Sui says the study didn't find a significant association between coffee
consumption and heart disease death. Further research is needed to look at any
connection between coffee and cancer, she says.
Gregg Fonarow, co-chief of clinical cardiology at the David Geffen School of
Medicine at UCLA, says, "Differences in other dietary factors, marital status and
other socioeconomic factors that were not adjusted for in this study may account
for some or all of these observations."
Fonarow, who was not involved in this research, says observational studies that
survey people about their coffee intake and tie that to how many died from any
cause have yielded mixed results.
Consider a 2012 study that found that coffee drinkers ages 50-71 had a lower risk
of death than their peers who did not consume coffee. In that study, researchers
from the National Cancer Institute, part of the National Institutes of Health, and
AARP found that the more coffee consumed, the more a person's death risk
declined.
Joseph DeRupo, a spokesman for the National Coffee Association of USA, says
the new study "presents findings that are out of step with prevailing science as
well as with widely accepted research methods."
Because coffee still stirs debate, Sui says more research is needed. In the
meantime, people should watch their coffee intake, she says. "Avoid excessive
coffee drinking."
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