Unlock document.
This document is partially blurred.
Unlock all pages and 1 million more documents.
Get Access
IM – 11 | 13
9. Cause: strong muscles
Exercise 11-28
[A = A causal statement is used as a premise; B = A causal statement is used as a conclusion; C
= A causal statement stands by itself as an unsupported claim.]
1. ▲A
2. A
3. C
4. ▲C
12. B
13. ▲B
14. C
Exercise 11-29
[P = paired unusual events principle; C = common variable principle; COV = covariation
principle]
IM – 11 | 14
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
3. C
4. COV
17. P
18. ▲P
19. P
20. COV
21. P
Exercise 11-30
Note: Though the instructions point out that “there is not necessarily a correct answer,” the
hypotheses that seem better are listed below. We provide more detail with the “triangled”
answers from the text.
1. ▲Answers (b) and (d) seem better in that one can at least see how their being true could
IM – 11 | 15
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
could reduce death by stroke.
5. All seem equally plausible.
Exercise 11-31
[A = this may well just be coincidence; B = the stated “cause” might really be the effect, and the
stated “effect” might really be the cause; C = the “cause” and “effect” might actually both be the
effects of a third thing; D = legitimate cause and effect]
1. ▲C (Mowing the grass results in both fumes and grass dust.)
2. B
10. ▲B (Maybe smart people eat more fish.)
11. B
12. C
13. ▲B (If there is more violence, there is likely to be more on TV.)
IM – 11 | 16
21. B
22. ▲A (Coincidence)
Exercise 11-32
Here are some suggestions or hints. Churchgoers are less likely to use tobacco; they are less
Exercise 11-33
1. ▲Ways it can happen; possible outcomes
Exercise 11-34
1. ▲No. After the first draw, the remaining deck is smaller.
2. .5 x .5 x .5 x .5 = .0625, or 6.25%
3. .5 or 50%
IM – 11 | 17
Exercise 11-35
First, notice that Lungren’s argument is an IBE, an inference to the best explanation. An
Exercise 11-36
What is called for ideally is a side-by-side comparison of classes that are identical in all relevant
respects except that in one class, attendance is required, and in the other, it isn’t. In the real
Exercise 11-37
a. Identify a causal hypothesis that might be raised by the passage.
b. Identify whether the passage reports on a randomized controlled experiment, a prospective
observational study, or a retrospective observational study.
1. ▲(a) Poker players’ confidence in the strength of their cards causes differences in arm
motions that can be interpreted by observers who are not poker experts. (b) This is a
IM – 11 | 18
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
2. (a) Piano instruction produces better performance on ratios and fractions. (b) We can’t tell
if it’s a true controlled experiment because we don’t know if the kids were divided into
3. We’ll summarize here (the details are obvious from the question itself). We can’t say with
4. ▲(a) The lead ophthalmologist thinks that leaving a light on at night deprives infant eyes
of the rest needed for nonmyopic development. In short, the causal hypothesis at issue is
5. This is a presumably randomized experiment that attempts to show that coffee grounds
suspended as sediment in coffee cause headaches. Unfortunately, the members of the
IM – 11 | 19
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
experimental group knew they were mixing coffee grounds into their pudding. This is
enough to give us headaches. The argument gives only weak support to the conclusion, in
our opinion.
6. (a) and (b) This randomized experiment is designed to test whether curcumin suppresses
made.
7. ▲(a) The causal hypothesis at issue is that exercise prevents colds. (b) Presumably this is a
randomized controlled experiment, although the report does not specifically state that the
subjects were randomly divided into two groups; and one part of the experiment is a
8. This huge randomized experiment was designed to test whether taking aspirin every other
day reduces the risk of heart attack. Because of the large numbers, the percentages can be a
little misleading. Out of the experimental group and the control group respectively, 104
IM – 11 | 20
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
9. (a) The South African, French, and Canadian studies are retrospective studies. The
Southern Illinois–Florida State study is a randomized experiment. (b) The hypotheses
tested were that cigarette smoking causes (vascular-associated) impotence and that nicotine
causes an immediate reduction in sexual arousal. (c) and (d) The South African study
10. ▲(a) High doses of androgen lower high density lipoprotein (HDL) levels in the blood. (b)
This is a prospective observational study. (c) There are two comparison groups: the sixteen
11. First study: The hypothesis is that vasectomies don’t cause disease. It’s a prospective
study. Over 10,000 men were in each of the groups (with and without vasectomies). Given
12. The causal hypothesis is that radiation-induced tumors are prevented by dietary restrictions
in rats exposed to high doses of X-rays; this is a randomized experiment. Forty-four rats
IM – 11 | 21
Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
are in the experimental group; an undisclosed number are in the control group. The
difference in frequency of effect (no tumors) was 80 percent (80 in the experimental group
versus 0 in the control group). The study strongly supports the hypothesis.
13. ▲(a) Cheating creates more positive feelings than guilty feelings. (b) This is a controlled
experiment. Its design does not require randomization except in the initial selection of
14. Causal claim: A behavior modification program aimed at Type A individuals prevents
heart attacks. The study is a randomized experiment. The experimental group consisted of
592 out of 862 predominantly male victims of heart attack; they were given group
counseling to ease Type A behavior. The matched control group consisted of 270 subjects
who received only cardiological advice. After three years, 7 percent of the experimental
group had suffered another heart attack, compared with 13 percent of the control group.
Exercise 11-38
1. The dog was reportedly more accurate than the standard PSA test, which surely is better
than chance at predicting whether an individual has prostate cancer.
Exercise 11-39
IM – 11 | 22
1. While prostate surgery may reduce your chances of dying of prostate cancer, it is not likely
to prolong your life. (The figures are compatible with a large number of people in the
surgery group dying on the operating table from their prostate surgery. That’s one way not
to die of prostate cancer.)
