Deck 3: What Do Samples Tell Us

Question 1

"Congress passed a ban on the sale of assault weapons. Now there is a move to repeal that ban. Do you agree that the ban on sale of assault weapons should be repealed?" That question is asked in an SRS of 1000 adults in Texas (population 18 million people) and a separate SRS of 1000 adults in Indiana (population 5.7 million people). Ninety-five percent confidence statements are made about the percents of all adults in both states who agree.
It would be cheaper to just announce the question on TV and ask people to call in with their opinions. Is this the best approach?

A) This is a good way to get information about the opinions of all adults.
B) This is a bad idea because if only a few people call in, the margin of error will be large.
C) This is a bad idea because allowing people to volunteer may result in large bias.
D) This is a bad idea because those who call in would not be a sample.
E) This is a bad idea because those who call in would not be a population.

Answer 1

This is a bad idea because allowing people to volunteer may result in large bias.

Question 2

The sports section of the East Mule Shoe Gazette runs a weekly question that readers can answer online. After the local university's football squad was beaten by its rival for the forty-second straight season, the question was "Do you think that the coach needs to go?" Of the 182 people who responded, 89 percent said Yes.
If one applied the quick method to the poll, one would obtain this 95 percent confidence interval:

A) 89% ± 7%
B) 89% ± 18%
C) 182 ± 7%
D) 82% ± 7%

Answer 2

89% ± 7%

Question 3

A Gallup Poll asked, "What is your favorite Summer Olympics event?" Of the people asked, 27 percent said, "swimming." Here is what Gallup says about the accuracy of this poll:
The results are based on telephone interviews with a sample of 1007 national adults, aged 18 years and older. For results based on the total sample of national adults, one can say with 95 percent confidence that the maximum error attributable to sampling and other random effects is plus or minus 3 percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
Which of these is a correct confidence statement based on this Gallup Poll, assuming there is no bias?

A) Gallup is 95 percent confident that between 24 percent and 30 percent of all adults would say swimming is their favorite Summer Olympic event.
B) Gallup is 95 percent confident that between 24 percent and 30 percent of the 1007 people interviewed would say swimming is their favorite Summer Olympic event.
C) There is a 95 percent chance that the opinions of the 1007 people interviewed fairly represent the opinions of all adults.
D) Among many samples, 95 percent will find that 27 percent of the people interviewed will say swimming is their favorite Summer Olympic event

Answer 3

Gallup is 95 percent confident that between 24 percent and 30 percent of all adults would say swimming is their favorite Summer Olympic event.

Question 4

Which of the following is correct?

A) Parameters describe population characteristics.
B) Parameters describe sample characteristics.
C) The population is a subset of the sample.
D) Statistics must be based on a simple random sample.

Question 5

Does coaching raise SAT scores? Because many students score higher on a second try, even without coaching, a study looked at a simple random sample of 4200 students who took the SAT twice. Of these, 500 had taken coaching courses between their two attempts at the SAT. The study compared the average increase in scores (out of the total possible score of 2400) for students who were coached with the average increase for students who were not coached.
The study is 95 percent confident that the difference between average scores for coached and uncoached students is between 28 and 57 points. To be 99 percent confident, the range of points would be:

A) wider because higher confidence requires a larger margin of error.
B) narrower because higher confidence requires a smaller margin of error.
C) wider because higher confidence requires a smaller margin of error.
D) narrower because higher confidence requires a larger margin of error.

Question 6

A Gallup Poll asked, "What is your favorite Summer Olympics event?" Of the people asked, 27 percent said, "swimming." Here is what Gallup says about the accuracy of this poll:
The results are based on telephone interviews with a sample of 1007 national adults, aged 18 years and older. For results based on the total sample of national adults, one can say with 95 percent confidence that the maximum error attributable to sampling and other random effects is plus or minus 3 percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
Suppose 500 people in the sample of 1007 adults were women. Gallup asked these 500 women, "What is your favorite Summer Olympic event?" Thirty-five percent said swimming was their favorite. Gallup gave a margin of error for this result. This margin of error is:

A) plus or minus 3 percentage points, just as for the overall poll.
B) less than plus or minus three points because the sample for this question is smaller.
C) greater than plus or minus three points because the sample for this question is smaller.
D) less than plus or minus three points because the population of swimming fans is smaller than the population of all adults.

Question 7

Increasing the size of an SRS has these beneficial effects:

A) the bias of the sample is reduced relative to smaller SRSs.
B) the margin of error is smaller than it is for smaller SRSs.
C) nonsampling errors become less important.
D) both A and B are correct.
E) answers A, B, and C are correct.

Question 8

The sports section of the East Mule Shoe Gazette runs a weekly question that readers can answer online. After the local university's football squad was beaten by its rival for the forty-second straight season, the question was "Do you think that the coach needs to go?" Of the 182 people who responded, 89 percent said Yes.
The number 89 percent is a

A) parameter.
B) reliability.
C) statistics.
D) margin of error.

Question 9

Do doctors in managed-care plans give less charity care? Researchers chose 60 communities at random and then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3 percent of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85 percent of their practice income from managed-care plans were significantly less likely than other doctors to provide charity care.
Some doctors who did not give any charity care may say that they did. If so, the study suffers from:

A) a large margin of error to take account of possible failure to be truthful.
B) sampling errors that require a better random sampling design.
C) bias: The sample result will systematically underestimate the true percent of doctors who give charity care.
D) bias: The sample result will systematically overestimate the true percent of doctors who give charity care.

Question 10

A Gallup Poll asked, "What is your favorite Summer Olympics event?" Of the people asked, 27 percent said, "swimming." Here is what Gallup says about the accuracy of this poll:
The results are based on telephone interviews with a sample of 1007 national adults, aged 18 years and older. For results based on the total sample of national adults, one can say with 95 percent confidence that the maximum error attributable to sampling and other random effects is plus or minus 3 percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
In Gallup's statement, "95 percent confidence" means (assuming there is no bias) that:

A) Gallup knows 95 percent of all adults would give the same answer that this poll found.
B) if Gallup were to repeat this poll many times, 95 percent of all the polls would find that 27 percent of the people interviewed would say swimming is their favorite Summer Olympic event.
C) this poll is one of the 95 percent of all Gallup polls that give correct results.
D) if Gallup were to repeat this poll many times, 95 percent of the results would be within plus or minus 3 percentage points of the truth about the population.

Question 11

Do doctors in managed-care plans give less charity care? Researchers chose 60 communities at random and then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3 percent of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85 percent of their practice income from managed-care plans were significantly less likely than other doctors to provide charity care.
For a simple random sample of size 10,881, the margin of error for 95 percent confidence is about:

A) ± 9.6%.
B) ± 3%.
C) ± 0.96%.
D) ± 0.0096%.

Question 12

If a sampling method is biased, then:

A) one needs to improve the sampling method to remove the bias.
B) one needs to increase the sample size to remove the bias.
C) one should sample from a larger population.
D) the sample statistic will be close to the population parameter.
E) the center of the distribution of the statistic will be close to the population parameter.

Question 13

A Gallup Poll asked, "What is your favorite Summer Olympics event?" Of the people asked, 27 percent said, "swimming." Here is what Gallup says about the accuracy of this poll:
The results are based on telephone interviews with a sample of 1007 national adults, aged 18 years and older. For results based on the total sample of national adults, one can say with 95 percent confidence that the maximum error attributable to sampling and other random effects is plus or minus 3 percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
Suppose 500 people in the sample of 1007 adults were women. Gallup asked these 500 women, "What is your favorite Summer Olympic event?" Thirty-five percent said swimming was their favorite. Gallup gave a margin of error for this result. Applying the quick method, one finds that the margin of error for 95 percent confidence changes when the sample size drops from 1007 to 500, from:

A) 4.5 percent to 3.2 percent.
B) 3.2 percent to 4.5 percent.
C) 3 percent to 1.5 percent.
D) 3 percent to 6 percent.

Question 14

A U.S. Census Bureau report on the income of Americans says, with 90 percent confidence, the median income of all California households in 2007 was $67,484, with a margin of error of ± $375. This means that:

A) 90 percent of all households had incomes in the range $67,484 ± $375.
B) the median income for all households in the country lies in the range $67,484 ± $375.
C) 90 percent of the households in the sample interviewed by the Census Bureau had incomes in the range $67,484 ± $375.
D) the Census Bureau got the result $67,484 ± $375 using a method that will cover the true median income 90 percent of the time when used repeatedly.

Question 15

Do doctors in managed-care plans give less charity care? Researchers chose 60 communities at random and then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3 percent of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85 percent of their practice income from managed-care plans were significantly less likely than other doctors to provide charity care.
The number 77.3 percent is:

A) a statistic because it describes a sample.
B) a statistic because it describes a population.
C) a parameter because it describes a sample.
D) a parameter because it describes a population.

Question 16

"Congress passed a ban on the sale of assault weapons. Now there is a move to repeal that ban. Do you agree that the ban on sale of assault weapons should be repealed?" That question is asked in an SRS of 1000 adults in Texas (population 18 million people) and a separate SRS of 1000 adults in Indiana (population 5.7 million people). Ninety-five percent confidence statements are made about the percents of all adults in both states who agree.
The margin of error for Indiana is:

A) the same as in Texas because the two SRSs are the same size.
B) larger than in Texas because there are fewer people in Indiana.
C) smaller than in Texas because there are fewer people in Indiana.
D) may be either smaller or larger than in Texas because the sample result varies due to chance.
E) smaller because everything is bigger in Texas.

Question 17

Does coaching raise SAT scores? Because many students score higher on a second try, even without coaching, a study looked at a simple random sample of 4200 students who took the SAT twice. Of these, 500 had taken coaching courses between their two attempts at the SAT. The study compared the average increase in scores (out of the total possible score of 2400) for students who were coached with the average increase for students who were not coached.
The report of the SAT study says, "With 95 percent confidence, one can say that students who are coached raise their average SAT scores by between 28 and 57 points more than students who are not coached." By "95 percent confidence," the report means that:

A) 95 percent of all students will increase their score by between 28 and 57 points if they are coached.
B) the average increase is between 28 and 57 points.
C) the study obtained the 28 to 57 point range by using a method that would give a correct answer in 95 percent of all samples.
D) 95 percent of all adults would believe the statement.

Question 18

To reduce the variability of estimates from a simple random sample, one should

A) use a smaller sample.
B) increase the bias.
C) use a count, not a percent.
D) use a larger sample.
E) use a percent, not a count.

Question 19

If one takes many simple random samples from the same population, one expects:

A) the same values of the statistic for each sample.
B) the values of the statistic will vary from sample to sample.
C) a different value of the parameter for each sample.
D) a problem with voluntary response.
E) a problem with bias.

Question 20

The margin of error for a poll is 4 percent. This means that:

A) 4 percent of those sampled did not answer the question asked.
B) there is a 95 percent confidence that the sample statistic is within 4 percent of the population parameter.
C) 4 percent of those sampled gave the wrong answer to the question asked.
D) 4 percent of the population was in the sample.
E) people's confidence in the statistic is 4 percent.

Question 21

Sale of spinach that is contaminated with e coli can cause food poisoning among consumers. A food inspector takes an SRS of 400 bags from all the bags of spinach shipped in one day. The laboratory reports that 19 of these bags had e coli contamination. Unknown to the producer, 1 percent of all bags shipped had e coli.
In this situation:

A) 1 percent is an estimate and 19 is a margin of error.
B) 1 percent is a parameter and 19 is a statistic.
C) 19 is a parameter and 1 percent is a statistic.
D) Both 1 percent and 19 are statistics.
E) Both 1 percent and 19 are parameters.

Question 22

When an opinion poll says that "with 95 percent confidence," the margin of error for its results is plus or minus 3 percentage points, this means that:

A) 95 percent of the people chosen for the sample were contacted.
B) between 92 percent and 98 percent of the people chosen for the sample were contacted.
C) the percent of people who said Yes to the question was between 92 percent and 98 percent.
D) one can be certain that the true population value is within ± 3 points of 95 percent.
E) 95 percent of all samples chosen, as this one was, give results within ± 3 points of the true population value.

Question 23

A confidence statement based on a probability sample says, "One can be 95 percent confident that between 72 percent and 78 percent of all adult Americans believe that the country needs a national health-care system." The phrase "95 percent confident" means that:

A) if one took many samples, about 95 percent of the resulting intervals would contain the true value.
B) the sampling frame lists 95 percent of all American adults.
C) 95 percent of the sample agreed that Americans need a national health-care system.
D) the margin of error covers 95 percent of all responses in the population.

Question 24

Sale of spinach that is contaminated with e coli can cause food poisoning among consumers. A food inspector takes an SRS of 400 bags from all the bags of spinach shipped in one day. The laboratory reports that 19 of these bags had e coli contamination. Unknown to the producer, 1 percent of all bags shipped had e coli.
A statistician tells the producer that the margin of error for a 95 percent confidence statement for these data is about plus or minus 2 percentage points. The producer therefore reports that between 2.8 percent and 6.8 percent (that's 4.8 percent ± 2 percent) of all the bags of spinach are contaminated. This isn't right: only 1 percent is contaminated. What went wrong?

A) The 4.8 percent is wrong-see the answer to the previous problem for the correct estimate.
B) A 95 percent confidence statement is only right for 95 percent of all possible samples. This must be one of the 5 percent for which one gets an incorrect conclusion.
C) The 4.5 percent is correct, and it's impossible for the truth to lie outside the margin of error, so there must be another mistake. Maybe the laboratory counted contaminated bags incorrectly.

Question 25

A recent survey asked a sample of 1010 people if they were baseball fans; 454 people in the sample said Yes. Assuming there is no bias, one can be 95 percent confident that the percent of all adults who are baseball fans is approximately between:

A) 41 percent and 49 percent.
B) 42 percent and 48 percent.
C) 40 percent and 50 percent.
D) 37 percent and 53 percent.
E) 34 percent and 56 percent.

Question 26

Sale of spinach that is contaminated with e coli can cause food poisoning among consumers. A food inspector takes an SRS of 400 bags from all the bags of spinach shipped in one day. The laboratory reports that 19 of these bags had e coli contamination. Unknown to the producer, 1 percent of all bags shipped had e coli.
If the producer took an SRS of 200 bags instead of 400, the new margin of error would be:

A) the same as before because the population of bags is the same.
B) smaller than before because the sample is smaller.
C) larger than before because the sample is smaller.
D) random in size and could be either larger or smaller than before.
E) impossible to determine because the size of the sample doesn't control the margin of error.

Question 27

When constructing a confidence interval, the "margin of error" means that if there is no bias:

A) every sample taken will come at least this close to the truth.
B) about half of the samples taken will come at least this close to the truth.
C) about 95 percent of all samples taken will come at least this close to the truth.
D) the sampling method is biased. Otherwise, the poll would always give the correct answer.
E) there are serious nonsampling errors. Otherwise, the poll would always give the correct answer.

Question 28

A Gallup Poll asked 1022 randomly chosen adults whether the failure of the government to solve major challenges facing the country was a "crisis," a "major problem," a "minor problem," or "not a problem." The proportion giving the response "a minor problem" was 14 percent. The margin of sampling error was plus or minus 3 percentage points. Assume a 95 percent confidence level and no bias. From the information given above, one can make which of the following statements? (Note that 14 percent ± 3 percent is 11 percent to 17 percent.)

A) Between 11 percent and 17 percent of the sample responded, "a minor problem."
B) Between 11 percent and 17 percent of all American adults would respond, "a minor problem."
C) There is a 95 percent confidence (but not certainty) that between 11 percent and 17 percent of the sample responded, "a minor problem."
D) There is a 95 percent confidence (but not certainty) that between 11 percent and 17 percent of all American adults would respond, "a minor problem."

Question 29

If the sample size is much smaller than the population size, the margin of error of a simple random sample depends on:

A) sample size.
B) population size.
C) both of the above.
D) neither of the above.

Question 30

A Pew Research Council Poll recently showed that 23 percent of Americans are religiously unaffiliated and among these, 61 percent believe in God. The poll contacted 35,071 adults by telephone. The margin of sampling error was plus or minus 0.6 (six-tenths) of a percentage point. Assume a 95 percent confidence level and no bias. The numbers 23 percent and 61 percent in the report on the poll results are:

A) parameters because they describe a population.
B) parameters because they describe a sample.
C) statistics because they describe a population.
D) statistics because they describe a sample.

Question 31

An opinion poll asks a sample of 1100 people whether they support reducing the number of legal immigrants to the United States; 53 percent of these 1100 people say Yes. The number 53 percent is a:

A) margin of error.
B) statistic.
C) bias.
D) parameter.
E) confidence.

Question 32

_____ in a sampling method means that the sample results will systematically misrepresent the population in the same way when one takes repeated samples.

A) Bias
B) Confounding
C) Comparison
D) Variability
E) Confidence level

Question 33

Before the 2016 presidential election, a national survey asked a sample of 2009 American adults what kind of president Donald Trump would be: 52 percent said "poor" or "terrible." The margin of error announced by news reports of this poll was approximately:

A) ± 6%
B) ± 4%
C) ± 3%
D) ± 2%
E) ± 0.02%

Question 34

Sale of spinach that is contaminated with e coli can cause food poisoning among consumers. A food inspector takes an SRS of 400 bags from all the bags of spinach shipped in one day. The laboratory reports that 19 of these bags had e coli contamination. Unknown to the producer, 1 percent of all bags shipped had e coli.
Based on the sample data, the producer estimates that the proportion of contaminated bags in the population is about:

A) 19 percent
B) 1.9 percent
C) 1 percent
D) 4.8 percent
E) 0.3 percent

Question 35

If one were to choose an SRS from a population, one could be sure that the _____, computed from the SRS, is a(n) _____ estimate of the population's true _____. One also knows that one can reduce the _____ of the result as desired, by taking a large enough sample.

A) parameter; variation; statistic; unbiasedness
B) parameter; unbiased; statistic; variation
C) statistic; variation; parameter; unbiasedness
D) statistic; unbiased; parameter; variation

Question 36

Suppose somebody wishes to estimate the percentage of students who smoke cigarettes at each of several colleges and universities. Two of the colleges are Rice University (enrollment 6621) and Indiana University (enrollment 48,000). The margin of error for an SRS of 5 percent of the students at each school will be:

A) smaller for Rice than for Indiana.
B) larger for Rice than for Indiana.
C) about the same at both schools.
D) either smaller or larger for Rice. It isn't possible to tell without seeing the sample results.

Question 37

If a Gallup Poll surveys a national sample of 3000 people rather than 1500 people, the margin of error of the sample result would be:

A) the same as for 1500 because the population is the same.
B) less than it would be for 1500 because the sample is now larger.
C) greater than it would be for 1500 because the sample is now larger.
D) either less or greater than it would be for 1500 because it depends on the chance outcome of the sample.
E) either less or greater than it would be for 1500. It's impossible to say, because sample size 3000 is not in the table.

Question 38

The Gallup organization conducts a poll to see how much support there is for a constitutional amendment guaranteeing the right to abortion. They announce that 23 percent of Americans are in favor of such an amendment, with a 95 percent confidence margin of error of 3.4 percent. If the results of the above poll were described using a 90 percent confidence statement, what would happen to the margin of error?

A) It would be greater than 3.4 percent.
B) It would be less than 3.4 percent.
C) It would still be 3.4 percent.
D) More information is needed to determine how the margin or error would change

Question 39

Which of the following is correct?

A) Statistics describe population characteristics.
B) Statistics describe sample characteristics.
C) The population is a subset of the sample.
D) Parameter and statistic are two names for the same thing.

Question 40

A typical opinion poll uses a sample size of between 1000 and 1500 people. The Current Population Survey samples 50,000 households every month to gather data on employment and unemployment. The main advantage of the much larger sample is that:

A) there is less bias in a large random sample.
B) a large random sample has a smaller margin of error.
C) a larger random sample allows use of stratified sampling.
D) nonsampling errors are smaller in a large random sample.

Question 41

A local planning commission is interested in finding out what proportion of its city's residents is opposed to constructing a new baseball stadium in the downtown area. A random sample of 1870 residents is obtained, and 41.2 percent of them are opposed to the stadium.
The commission is 95 percent confident that between _____ of the city's residents are opposed to constructing a new baseball stadium in the downtown area.

A) 1867.7 and 1872.3
B) 41.187 percent and 41.223 percent
C) 38.9 percent and 43.5 percent
D) 41.2 percent and 58.8 percent

Question 42

A recent survey of 174,745 randomly selected U.S. adults studied the importance of religion to Americans in each state.
The survey found that nationwide 40 percent said that they were very religious. But in New Hampshire, the least religious state, only 20 percent answered that they were "very religious." The sample included 1000 respondents from New Hampshire. The margin of error in a 95 percent confidence interval for the proportion of all adults who are very religious is:

A) larger for New Hampshire than for the nation.
B) the same for New Hampshire and for the nation.
C) smaller for New Hampshire than for the nation.
D) random, so one can't make a comparison.

Question 43

A local planning commission is interested in finding out what proportion of its city's residents is opposed to constructing a new baseball stadium in the downtown area. A random sample of 1870 residents is obtained, and 41.2 percent of them are opposed to the stadium.
A 95 percent confidence interval was created for the proportion of the city's residents who are opposed to constructing a new baseball stadium in the downtown area. Decreasing the sample size will:

A) result in a narrower interval because there will be less information.
B) result in a narrower interval because the margin of error will decrease.
C) result in a wider interval because the margin of error will increase.
D) result in a wider interval because the average scores will change.
E) not affect the confidence interval at all.

Question 44

A local planning commission is interested in finding out what proportion of its city's residents is opposed to constructing a new baseball stadium in the downtown area. A random sample of 1870 residents is obtained, and 41.2 percent of them are opposed to the stadium.
In this sample, the proportion of the city's residents opposed to constructing a new baseball stadium in the downtown area is:

A)770.
B) 2.3 percent.
C) 41.2 percent.
D) 0.023 percent.

Question 45

What is the most important issue facing the next president? In a January 2016 survey of 1022 adults, the Gallup organization found that Republicans and Democrats agreed on the top four issues, and terrorism was reported as the top challenge by 17 percent of respondents, with a margin of error of plus or minus 4 percentage points at 95 percent confidence level.
In this sample, the proportion of Americans who feel that the most important issue facing the next president is terrorism is:

A)170.
B) 95 percent.
C) 17 percent.
D) 4 percent.

Question 46

A local planning commission is interested in finding out what proportion of its city's residents is opposed to constructing a new baseball stadium in the downtown area. A random sample of 1870 residents is obtained, and 41.2 percent of them are opposed to the stadium.
In this sample, the margin of error is

A)770.
B) 2.3 percent.
C) 41.2 percent.
D) 0.023 percent.

Question 47

_____ in a sampling method describes how spread out the values of the sample statistic are when one takes repeated samples.

A) Bias
B) Confounding
C) Variability
D) Confidence level

Question 48

A recent survey of 174,745 randomly selected U.S. adults studied the importance of religion to Americans in each state.
Of those questioned in the poll, 29 percent said that they were "moderately religious." The number 29 percent is a:

A) statistics.
B) margin of error.
C) parameter.
D) confidence level.

Question 49

A local planning commission is interested in finding out what proportion of its city's residents is opposed to constructing a new baseball stadium in the downtown area. A random sample of 1870 residents is obtained, and 41.2 percent of them are opposed to the stadium.
A 95 percent confidence interval was created for the proportion of the city's residents who are opposed to constructing a new baseball stadium in the downtown area. A "95 percent confidence" means that:

A) 95 percent of all residents oppose constructing a new stadium in the downtown area.
B) the interval was obtained by using a method that would give a range containing the true value for 95 percent of all samples.
C) the interval contains the true proportion of all residents who oppose constructing a new stadium in the downtown area.
D) 95 percent of all educated adults would believe the statement.

Question 50

For a simple random sample of size 4761, the margin of error for 95 percent confidence is about:

A) ± 0.0145%.
B) ± 1.45%.
C) ± 0.021%.
D) ± 0.00021%.

Question 51

What is the most important issue facing the next president? In a January 2016 survey of 1022 adults, the Gallup organization found that Republicans and Democrats agreed on the top four issues, and terrorism was reported as the top challenge by 17 percent of respondents, with a margin of error of plus or minus 4 percentage points at 95 percent confidence level.
In this sample, the margin of error is:

A)170.
B) 95 percent.
C) 17 percent.
D) 4 percent.

Question 52

What is the most important issue facing the next president? In a January 2016 survey of 1022 adults, the Gallup organization found that Republicans and Democrats agreed on the top four issues, and terrorism was reported as the top challenge by 17 percent of respondents, with a margin of error of plus or minus 4 percentage points at 95 percent confidence level.
There is a 95 percent confidence that between 13 percent and 21 percent of Americans feel that the most important issue facing the next president is terrorism. Increasing the sample size will:

A) result in a wider interval because there'll be more information.
B) result in a wider interval because the margin of error will increase.
C) result in a narrower interval because the margin of error will decrease.
D) result in a narrower interval because the average scores will change.
E) not affect the confidence interval at all.

Question 53

What is the most important issue facing the next president? In a January 2016 survey of 1022 adults, the Gallup organization found that Republicans and Democrats agreed on the top four issues, and terrorism was reported as the top challenge by 17 percent of respondents, with a margin of error of plus or minus 4 percentage points at 95 percent confidence level.
There is a 95 percent confidence that between 13 percent and 21 percent of Americans feel that the most important issue facing the next president is terrorism. For a 99 percent confidence, the range of points would be:

A) wider because higher confidence requires a larger margin of error.
B) narrower because higher confidence requires a smaller margin of error.
C) wider because higher confidence requires a smaller margin of error.
D) narrower because higher confidence requires a larger margin of error.

Question 54

What is the most important issue facing the next president? In a January 2016 survey of 1022 adults, the Gallup organization found that Republicans and Democrats agreed on the top four issues, and terrorism was reported as the top challenge by 17 percent of respondents, with a margin of error of plus or minus 4 percentage points at 95 percent confidence level.
With these results, one may say, "With 95 percent confidence, one can say that between 13 percent and 21 percent of Americans feel that the most important issue facing the next president is terrorism." What "95 percent confidence" means is that:

A) 95 percent of all Americans will say terrorism is the most important issue.
B) one can be certain that between 13 percent and 21 percent of Americans will say terrorism is the most important issue.
C) Gallup obtained the 13 percent to 21 percent range by using a method that would give a range containing the true value for 95 percent of all samples.
D) 95 percent of all educated adults would believe the statement.

Question 55

In an SRS of students, 23 percent said they smoked, while another 16 percent said they "hardly ever" smoked. The numbers 23 percent and 16 percent are:

A) confidence levels.
B) samples.
C) parameters.
D) margins of error.
E) statistics.