978-1259690877 Test Bank Chapter 11 Part 3

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84.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

SUSANVILLE—Fewer than 20 percent of college professors consider themselves shy,

according to a new study by two psychologists. “We were surprised by this result because

other studies have reported that almost 50 percent of adult Americans think of themselves

as shy,” said Elliot Smalley, professor at Colusa State University. “College professors are

sometimes thought to be an introverted lot, and so we expected perhaps a majority to

think of themselves as shy,” he said.

Smalley and his associate, John Mahmoud, interviewed 150 college professors who were

identified by administrators at twenty-five American universities as typical faculty. The

universities were selected by a random procedure from a list of American colleges and

universities, Smalley said.

This is a poor generalization. University administrators might be apt to state the first

professors who come to mind, and professors selected in this manner might tend to be

among the more outspoken faculty. Truly shy, introverted faculty might well be unknown to

most administrators at a large university.

85.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Gridley has been going to the Silver Dollar Fair every year for the past fifteen years. An

acquaintance suggests they go to the fair, but “For God’s sake, let’s don’t eat there, we’ll

die.” Gridley knows better; he’s never even once gotten sick from Silver Dollar food.

No fallacy.

86.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

A random survey of 1,000 callers to a drug hotline number produced the following results:

535 of the callers were heavy users of either cocaine freebase, amphetamines, or heroin;

220 were “recreational” users of cocaine or hashish; 92 were not drug users at all; and the

remainder refused to answer the survey questions. This should put to rest the claim that

most people who take drugs are of the occasional, “recreational” type.

The sample in this argument is badly biased. A typical heavy user of a drug is much more

likely to get into a crisis situation and thus more likely to call a hotline number than a

typical “recreational” user.

87.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

ATLANTA (UPI)—A long-term federal study by the National Centers for Disease Control of

13 million U.S. births shows increases in the rate of eleven different types of birth defects,

including a 17.5 percent yearly average increase in patent ductus arteriosus and a 10.8

percent increase for ventricular septal defects, over a fourteen-year period. The study was

conducted by the Birth Defects Monitoring Program of the CDC, which collected its data

from hospitals across the country. From 1970 to 1983, over 13 million births were

monitored. [An adaptation]

“Hospitals across the country” is vague, but this is almost certainly a reputable scientific

study, and the sample is extremely large. A generalization from these results to the

American population as a whole should be sound.

88.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

FRESNO—In a new study of dangerous Halloween pranks, Fresno State University

sociologist Joel Best has documented the exact number of American children killed or

seriously injured by anonymously given, booby-trapped Halloween treats. Best reviewed

supposedly real Halloween horror stories appearing from 1958 to 2004 in the

New York

Times

, the

Chicago Tribune

, the

Los Angeles Times

, and the

Fresno Bee

. He did not find a

single case in which a Halloween treat anonymously given to a child caused serious harm.

He concluded that the infamous Halloween sadist is an “urban myth.”

—Adapted from a McClatchy News Service release

The question is whether the “exact number” of American children killed or seriously

injured by anonymously given Halloween tricks can be determined by looking at the

incidents reported in the four newspapers mentioned. There may have been a few

incidents not reported in these newspapers, but we’d be surprised if there were many.

Events of this type tend to attract too much attention not to be reported in at least one of

these sources.

89.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Haslett wanted to know what percentage of students at his college vote in local elections.

He asked each of his professors (he was a political science major) to ask for a show of

hands in his classes, so he could make a count. He found that 45 percent of the 120

classmates polled vote in local elections. He concludes that about 45 percent of the

students at his college vote in those elections.

The sample is large enough to be somewhat reliable, although Haslett should not be

surprised by a substantial deviation from his 45 percent projection. A more serious

problem is that Haslett’s poll may have been taken in political science classes (or at least

mainly in political science classes) and that people who take such classes may be more

interested in political matters and hence more likely to vote in any election. The possibility

of bias is substantial.

90.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

A survey was made in 1948 in which a large number of names were randomly selected

from the telephone book of a large city. The individuals called were asked whether they

preferred Truman or Dewey in the presidential race. Over half of the respondents named

Dewey, so the pollsters concluded that Dewey would carry the city and region.

The principal problem with this survey is that in 1948 many voters did not have telephones

and thus had no chance of being selected. Since possession of a telephone was linked

with a person’s economic status, and economic status helps determine political views, the

sample was badly biased.

91.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

As part of his work for NASA, Dr. Murdock was asked to find out what percentage of

Americans saw Halley’s comet when it was last visible. He randomly selected three

cities—Seattle, Cleveland, and Boston—and polled several hundred randomly selected

individuals from these cities. His findings are that fewer than 5 percent of Americans saw

the comet.

It makes no difference whether the cities and the individuals were randomly selected.

Inhabitants of large cities, especially northern big cities, would be less likely to see the

comet because of city lights, clouds, air pollution, and latitude.

92.

In evaluating the following generalization(s), identify sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Let’s say that according to statewide studies done in Montana and Virginia, the infant

mortality rate for these two states averaged 10.5 per thousand live births. Could this figure

be generalized to the infant mortality rate in the United States? What factors might be

relevant to the generalization?

Montana and Virginia provide a large and reasonably good sample, although there may be

a bias toward rural areas and small towns over large urban areas. We would want to know

about Montana’s and Virginia’s resident–to-doctor ratios, their ratios of residents to

hospital beds, the level of prenatal education available in the two states, and similar

matters. The more similar these possibly relevant factors are in Montana and Virginia to

the remainder of the country, the stronger the argument.

93.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Osteoporosis is a degeneration of bone tissue that afflicts between fifteen and twenty

million Americans and leads to approximately 1.3 million bone fractures every year. The

condition is found mainly among women. A conference sponsored by the National

Institutes of Health in 1994 reported that calcium was one of the “mainstays of prevention

and management of osteoporosis.” In a localized study designed to help predict the future

incidence of osteoporosis in women in a midwestern community, a county hospital did a

survey on calcium intake. It selected five hundred women at random and asked them to

keep a record of their food and dietary supplements for one month. The data were

analyzed to determine the amounts of calcium each woman received. It was determined

that 85 percent of the surveyed women received less calcium than the recommended

amount of 1,000 to 1,500 milligrams per day. County medical authorities concluded that

about 85 percent of the community’s women were getting less than the recommended

intake of calcium. They also concluded that local medical facilities would soon see an

increase in the number of cases of osteoporosis as the calcium deficiency showed its

effects. Given just the information presented here, how much confidence would you have

in these conclusions?

The first conclusion is less solid than it might appear. The survey was done during one

month, and diets change during the course of a year. More dairy products may be

consumed during one time of the year than others; certainly some vegetables are

consumed on a varying seasonal basis. Hence, the study may accurately reflect only the

calcium intake in the population during that month of the year. Another problem with the

11–50

calcium at age twenty-four but who increase their intake by the time they are thirty-five

may be no more likely to suffer osteoporosis than those whose intake is high during their

entire lives.)

The second conclusion does not follow at all. The insufficient intake of calcium may have

been going on for years; so the incidence of osteoporosis may remain exactly the same in

the future.

94.

In evaluating the following generalization(s), identify sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Seventy-two percent of those interviewed at a luncheon sponsored by the Camellia

Chamber of Commerce favored local tax incentives to attract new businesses. Would this

finding generalize to the Camellia population?

No. This is not likely to be a representative sample.

95.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

A majority of Americans think that tobacco companies should be prohibited from

advertising their products. In a survey of 1,213 adults, 86 percent said that prohibiting

tobacco advertising would lower smoking rates. The results of the nationwide telephone

survey, conducted by American Opinion Research, Inc., were published in this week’s

edition of

Research Fact

. Spokespersons for the American Tobacco Council had no

immediate comment on the findings.

It is not clear from this passage whether a majority of the respondents actually think that

tobacco advertising should be prohibited. The 86 percent said something else: that doing

so would lower smoking rates. Whether they would outlaw tobacco advertising is not

known.

96.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

A poll of fifty weight lifters at a southern California gym determined that thirty-three payed

close attention to their diets as well as to their exercise. Of those thirty-three, twenty-five

(50 percent of the original fifty) made it a point to eat more than the minimum daily

amount of protein for large adults, and twenty (40 percent of the original fifty) took vitamin

pills and other dietary supplements. The chain of health-food stores that took the poll

concluded that weight lifters constitute a substantial market for its products, since it is

likely that 40 percent of all weight lifters across the country take vitamin pills and

supplements and that an additional 10 percent are at least highly conscious of their diets.

The health-food chain had best not invest too much in attracting this new market. The

first flaw in the survey is technical: the sample is too small to give a very detailed picture

of weight lifters’ habits. Even if nothing else were wrong with the survey, strong

confidence (95 percent) would be justified only in the claim that from about 36 to 64

percent of the weight lifters nationwide make sure to eat more than the usual amount of

protein—not a very precise conclusion (see the error margin table [Table 10-1] in the text,

page 360). A more important flaw in the survey is that the interviews are confined to

clients of only one gym. Information is often passed around among people who frequent

the same establishments, and there may be trends or fads or a particular bit of useful

97.

Evaluate the following generalization(s), identifying sample, population, attribute of

interest, and the extent to which the claims involved are knowable. Consider carefully the

size and diversification of the sample and the extent to which the population differs or

may differ from the sample; remember, what’s important is that the sample be

representative.

Thirty percent of American people ages nineteen to thirty-nine diet at least once a month,

according to a news syndicate poll released last November. These findings are based on

telephone interviews with a random sample of people listed in the Los Angeles telephone

directory.

A generalization about the subject based on a sample of people would be unreliable,

especially since people in southern California are more likely to be aspiring models and

actors, beachgoers, and tend to pay more attention to their physiques.

98.

In the following passage, identifying sample, population, attribute of interest, and the

extent to which the claims involved are knowable. Consider carefully the size and

diversification of the sample and the extent to which the population differs or may differ

from the sample; remember, what’s important is that the sample be representative. Do you

find any flaw in our professor’s reasoning about the usefulness of the survey for her own

purposes? Should she believe that the more people who have home offices, the more

likely her own will escape attention from the IRS?

A college professor converted one room of her house into a home office and intended to

deduct her expenses on her federal income tax return. She wondered how many other

college faculty had done the same, thinking that the more who deducted home offices, the

less likely her own return would be noticed by the IRS and hence the less likely she would

be audited. So she decided to do her own informal survey of her colleagues to see how

many of them had home offices. She sent out a questionnaire of three questions to all

1,200 instructors at her campus, and she received 950 responses. (Her promise to share

the results of the survey apparently motivated faculty to respond.)

As it turned out, 32 percent of her respondents answered yes to the question, “Do you

maintain an office at home?” Half of these also answered yes to the question, “Do you

deduct your home office expenses on your federal income tax return?” And 24 percent of

the entire group of respondents answered yes to the question, “Is your campus office

adequate?”

This is not a question about the criteria for evaluating statistical generalizations, but

rather about the assumption that motivated the study. It does us no good to produce

studies to answer questions if they are the wrong questions to begin with. In this case, it

may be that the IRS will turn more attention to home office deductions if there are enough

99.

In the following passage, identifying sample, population, attribute of interest, and the

extent to which the claims involved are knowable. Consider carefully the size and

diversification of the sample and the extent to which the population differs or may differ

from the sample; remember, what’s important is that the sample be representative. Would

our professor’s conclusion, “About 32 percent of college faculty nationwide maintain home

offices,” be more likely if she had included faculty from other institutions among her

survey? Why?