Name: __________________________ Date: _____________
1. In order to select a sample of undergraduate students in the United States, I select a simple random
sample of four states. From each of these states, I select a simple random sample of two colleges or
universities. Finally, from each of these eight colleges or universities, I select a simple random sample
of 20 undergraduates. My final sample consists of 160 undergraduates. This is an example of
A) simple random sampling.
B) stratified random sampling.
C) systematic random sampling.
D) convenience sampling.
E) multistage sampling.
2. A small college has 500 male and 600 female undergraduates. A simple random sample of 50 of the
male undergraduates is selected, and, separately, a simple random sample of 60 of the female
undergraduates is selected. The two samples are combined to give an overall sample of 110 students.
The overall sample is
A) a simple random sample.
B) a stratified random sample.
C) a multistage sample.
D) a convenience sample
E) all of the above.
3. Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral
scent could improve a person's learning ability in certain situations. They had 22 people work through a
pencil-and-paper maze six times, three times while wearing a floral-scented mask and three times
wearing an unscented mask. The three trials for each mask closely followed one another. Testers
measured the length of time it took subjects to complete each of the six trials. They reported that, on
average, subjects wearing the floral-scented mask completed the maze more quickly than those wearing
the unscented mask, although the difference was not statistically significant. This study is
A) a convenience sample.
B) an observational study, not an experiment.
C) an experiment, but not a double-blind experiment.
D) a controlled study.
E) a double-blind experiment.
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4. The six people listed below are enrolled in a statistics course taught by means of television. Use the list
of random digits
27102 56027 55892 33063 41842 81868 71035 09001 43367 49497 54580 81507
starting at the beginning of the list, to choose a simple random sample of size three to be interviewed in
detail about the quality of the course. Use the labels attached to the six names.
1. Moore
2. Casella
3. Santner
4. Goel
5. Jones
6. Klein
The sample you obtain is
A) Casella, Moore, and Jones.
B) Casella, Moore, and any other name.
C) Moore, Casella, and again Casella.
D) any set of three names, but we must exclude Casella.
E) 2, 7, and 1.
Use the following to answer questions 5-6:
Choose a simple random sample of size three from the following employees of a small company.
1. Bechhofer
2. Brown
3. Ito
4. Kesten
5. Kiefer
6. Spitzer
7. Taylor
8. Wald
9. Weiss
Use the numerical labels attached to the names above and the list of random digits below. Read the list of
random digits from left to right, starting at the beginning of the list.
11793 20495 05907 11384 44982 20751 27498 12009 45287 71753 98236 66419 84533
5. Referring to the information above, the simple random sample is
A) 117.
B) Bechhofer, Ito, Weiss.
C) Bechhofer, Taylor, Weiss.
D) Kesten, Kiefer, Taylor.
E) Bechhofer, then Bechhofer again, then Taylor.
6. If we used another list of random digits to select the sample, which of the following statements would
be true?
A) We would get the same result that we obtained with the list used here.
B) We would get the same names as those obtained from the sample listed here.
C) We would get at most one name in common with the sample obtained here.
D) It would be just as likely that the sample that we obtained here would be selected as any other set
of three names.
E) We would get a completely different sample than that obtained with the list used here.
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7. In order to determine if smoking causes cancer, researchers surveyed a large sample of adults. For each
adult they recorded whether the person had smoked regularly at any period in his or her life and
whether the person had cancer. They then compared the proportion of cancer cases in those who had
smoked regularly at some time with the proportion of cases in those who had never smoked regularly at
any point. The researchers found there was a higher proportion of cancer cases among those who had
smoked regularly than among those who had never smoked regularly. This is
A) a matched pairs study.
B) an experiment, but not a double-blind experiment.
C) a double-blind experiment.
D) a block design.
E) an observational study.
8. In a recent study, a random sample of children in grades 2 through 4 showed a significant negative
relationship between the amount of homework assigned and student attitudes. This is an example of
A) an experiment.
B) an observational study.
C) the establishing of a causal relationship through correlation.
D) a block design, with grades as blocks.
E) a cause and effect relationship.
9. A basketball player makes 2/3 of his free throws. To simulate a single free throw, which of the
following assignments of digits to making a free throw are appropriate?
A) 0 and 1 correspond to making the free throw and 2 corresponds to missing the free throw.
B) 01, 02, 03, 04, 05, 06, 07, and 08 correspond to making the free throw and 09, 10, 11, and 12
correspond to missing the free throw.
C) Use a die and let 1, 2, 3, and 4 correspond to making a free throw while 5 and 6 correspond to
missing a free throw.
D) A, B, and C are correct.
E) Neither A, B, nor C is correct.
10. Two variables in a study are said to be confounded if
A) one cannot separate their effects on a response variable.
B) they are highly correlated.
C) one does not explain the other.
D) one of them is a placebo.
E) they do not have a normal distribution.
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11. A study of the effects of running on personality involved 231 male runners who each ran about 20
miles a week. The runners were given the Cattell Sixteen Personality Factors Questionnaire, a 187-item
multiple-choice test often used by psychologists. A news report (New York Times, Feb. 15, 1988)
stated, “The researchers found statistically significant personality differences between the runners and
the 30-year-old male population as a whole.” A headline on the article said, “Research has shown that
running can alter one's moods.” Which of the following statements is true?
A) This study was not a designed experiment.
B) This study was an experiment, but not a double-blind experiment.
C) This study was a blocked experiment.
D) This study was a randomized, double-blind experiment.
E) This study was a double-blind experiment, but not a randomized experiment.
12. A stratified random sample corresponds to which of the following experimental designs?
A) A block design.
B) A double-blind experiment.
C) An experiment with a placebo.
D) A matched pairs design.
E) A confounded, nonrandomized study.
13. A sociologist wants to study the attitudes of American male college students toward marriage and
husband and wife relations. She gives a questionnaire to 25 of the men enrolled in Sociology 101 at her
college. All 25 complete and return the questionnaire. The sample in this situation is
A) all men taking a comparable sociology class.
B) all male students in the class planning on marriage.
C) all the men in the Sociology 101 class.
D) all married men in the Sociology 101 class.
E) the 25 men who received and returned the questionnaire.
14. The number of undergraduates at Johns Hopkins University is approximately 2000, while the number
at Ohio State University is approximately 40,000. At both schools a simple random sample of about
3% of the undergraduates is taken. We conclude that
A) the sample from Johns Hopkins is more accurate than the sample from Ohio State.
B) the sample from Ohio State University is about 20 times more accurate than the sample from John
Hopkins University.
C) the sample from Johns Hopkins has the same accuracy as the sample from Ohio State.
D) it is impossible to make any statements about the accuracies of the two samples since the students
surveyed were different.
E) the sample from Johns Hopkins is less accurate than the sample from Ohio State.
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15. A news release for a diet products company reports: “There's good news for the 65 million Americans
currently on a diet.” Its study showed that people who lose weight can keep it off. The sample was 20
graduates of the company's program who endorse it in commercials. The results of the sample are
probably
A) biased, overstating the effectiveness of the diet.
B) biased, understating the effectiveness of the diet.
C) unbiased because all 20 people lost weight.
D) biased, but they could be more accurate. A larger sample size should be used.
E) unbiased since these are nationally recognized individuals.
16. For one kindergarten class in his district, a researcher determines which children already can read
simple words and which children cannot upon entering kindergarten. The children are followed until
third grade, at which point they are tested to determine the grade level at which they are reading. Those
children who were reading simple words on entering kindergarten are found to be reading at a higher
level than those who could not read simple words on entering kindergarten. The researcher
A) can conclude that children should be taught to read in preschool, as there are clear benefits to
reading early.
B) cannot conclude that being able to read before entering kindergarten is beneficial, as there may be
confounding variables in this study.
C) needs to have taken a random sample of kindergarten students instead of one class to conclude a
cause-and-effect relationship.
D) needs to check the reading level of the children's parents.
E) needs to retest in sixth grade or no conclusions can be reached.
Use the following to answer questions 17-18:
A study of human development showed two types of movies to groups of children. Crackers were available in a
bowl, and the investigators compared the number of crackers eaten by children watching the different kinds of
movies. One kind of movie was shown at 8 a.m. (right after the children had breakfast) and another at 11 a.m.
(right before the children had lunch). It was found that during the movie shown at 11 a.m., more crackers were
eaten than during the movie shown at 8 a.m.. The investigators concluded that the different types of movies had
an effect on appetite.
17. The results cannot be trusted because
A) the study was not double-blind. Neither the investigators nor the children should have been aware
of which movie was being shown.
B) children are usually too sleepy early in the morning to watch movies.
C) the investigators should have used several bowls, with crackers randomly placed in each.
D) the time the movie was shown is a confounding variable.
E) the investigators were biased. They knew beforehand what they hoped the study would show.
18. The response variable in this experiment is
A) the number of crackers eaten.
B) the different kinds of movies.
C) the children in the study.
D) the bowls.
E) the time the movie was shown.
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19. In order to assess the effects of exercise on reducing cholesterol, a researcher sampled 50 people from a
local gym who exercised regularly and 50 people from the surrounding community who did not
exercise regularly. They each reported to a clinic to have their cholesterol measured. The subjects were
unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of
whether subjects exercised regularly or not. This is
A) an observational study.
B) an experiment, but not a double-blind experiment.
C) a controlled study.
D) a matched-pairs experiment.
E) a double-blind experiment.
20. In order to investigate whether women are more likely than men to prefer Democratic candidates, a
political scientist selects a large sample of registered voters, both men and women. She asks every
voter whether they voted for the Republican or the Democratic candidate in the last election. This is
A) an observational study.
B) a multistage sample.
C) a double-blind experiment.
D) a block design.
E) a systematic survey.
21. Which of the following is not a major principle of experimental design?
A) control.
B) replication.
C) randomization.
D) segmentation.
E) comparison.
22. A simple random sample of 1200 adult Americans is selected, and each person is asked the following
question:
In light of the huge national deficit, should the government at this time spend additional money to
establish a national system of health insurance?
Only 39% of those responding answered yes. This survey
A) is reasonably accurate since it used a large, simple random sample.
B) needs to be larger since only about 24 people were drawn from each state.
C) probably understates the percentage of people that favor a system of national health insurance.
D) is very inaccurate, but neither understates nor overstates the percentage of people that favor a
system of national health insurance. Since simple random sampling was used, it is unbiased.
E) probably overstates the percentage of people that favor a system of national health insurance.
23. A researcher conducts a study to investigate the effect of exercise and diet on mood. The factors in this
study are
A) the length of time a person exercised.
B) whether the experiment was double-blind.
C) the number of subjects.
D) exercise and diet.
E) whether randomization and placebos were used.
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24. A 1992 Roper poll found that 22% of Americans say that the Holocaust may not have happened. The
actual question asked in the poll was:
Does it seem possible or impossible to you that the Nazi extermination of the Jews never happened?
Twenty-two percent responded “possible.” The results of this poll cannot be trusted because
A) undercoverage is present. Obviously those people who did not survive the Holocaust could not be
in the poll.
B) we don't know if the respondents were randomly selected.
C) we do not know who conducted the poll or who paid for the results.
D) nonresponse is present. Many people will refuse to participate and those that do will be biased in
their opinions.
E) the question is worded in a confusing manner.
25. A marketing research firm wishes to determine if the adult men in Laramie, Wyoming, would be
interested in a new upscale men's clothing store. From a list of all residential addresses in Laramie, the
firm selects a simple random sample of 100 and mails a brief questionnaire to each. The population of
interest is
A) all adult men in Laramie, Wyoming.
B) all residential addresses in Laramie, Wyoming.
C) the members of the marketing firm that actually conducted the survey.
D) the 100 addresses to which the survey was mailed.
E) the people who respond to the questionnaire.
Use the following to answer questions 26-27:
Twelve people who suffer from chronic fatigue syndrome volunteer to take part in an experiment to see if shark
fin extract will increase one's energy level. Eight of the volunteers are men and four are women. Half of the
volunteers are to be given shark fin extract twice a day and the other half a placebo twice a day. We wish to
make sure that four men and two women are assigned to each of the treatments, so we decide to use a block
design with the men forming one block and the women the other.
26. Referring to the information above, a block design is appropriate in this experiment if
A) we believe men and women will respond differently to treatments.
B) gender equity is an important legal consideration in this study.
C) we couldn't find an equal number of men and women who suffer from low energy level.
D) we want the conclusions to apply equally to men and women.
E) all of the above.
27. Referring to the information above, suppose one of the researchers is responsible for determining if a
subject displays an increase in energy level. In this case, we should probably
A) use two placebos.
B) use stratified sampling to assign subjects to treatments.
C) use fewer subjects but observe them more frequently.
D) assign the subjects randomly to each group.
E) conduct the study as a double-blind experiment.
Page 7
Use the following to answer questions 28-29:
A television station is interested in predicting whether voters in its viewing area are in favor of federal funding
for abortions. It asks its viewers to phone in and indicate whether they support/are in favor of or are opposed to
this policy. Of the 2241 viewers who phoned in, 1574 (70.24%) were opposed to federal funding for abortions.
28. Referring to the information above, the viewers who phoned in are
A) a voluntary response sample.
B) a convenience sample.
C) a probability sample.
D) a population.
E) a simple random sample.
29. Referring to the information above, the sample obtained is
A) a simple random sample.
B) a single-stage sample.
C) a census.
D) close to the actual proportion of the population who support/oppose federal funding for abortions.
E) probably biased.
Use the following to answer questions 30-32:
One hundred volunteers who suffer from severe depression are available for a study. Fifty are selected at
random and are given a new drug that is thought to be particularly effective in treating severe depression. The
other 50 are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all
volunteers after four weeks in order to determine if there has been substantial improvement in the severity of the
depression.
30. The study described above would be double-blind if
A) neither drug had any identifying marks on it.
B) all volunteers were not allowed to see the psychiatrist nor the psychiatrist allowed to see the
volunteers during the session in which the psychiatrist evaluated the severity of the depression.
C) neither the volunteers nor the psychiatrist knew which treatment any person had received.
D) the psychiatrist didn't tell the volunteers which drug they were receiving.
E) all of the above.
31. The factor in the study above is
A) which treatment the volunteers receive.
B) the length of time for the treatment.
C) the extent to which the depression was reduced.
D) the use of a psychiatrist to evaluate the severity of depression.
E) the use of randomization and the fact that this was a comparative study.
Page 8
32. Referring to the study described above, suppose volunteers were first divided into groups of men and
women, and then half of the men were randomly assigned to the new drug and half of the women were
assigned to the new drug. The remaining volunteers received the other drug. This would be an example
of
A) replication.
B) confounding. The effects of gender will be mixed up with the effects of the drugs.
C) a block design.
D) a matched-pairs design.
E) a stratified design.
33. An amateur gardener decides to change varieties of tomatoes for this year to see if the yield is
improved. He put in six plants the previous year and puts in six plants this year using the same part of
the garden. The average yield per plant was 11.3 pounds per plant in the previous year and 14.5 pounds
per plant using the new variety. This is an example of
A) a matched pairs experiment.
B) an observational study, not an experiment.
C) the elimination of all confounding variables by design, since the gardener used the same part of
the garden in both years.
D) a multistage design, since two years were involved.
E) an experiment.
34. You are testing a new medication for relief of depression. You are going to give the new medication to
subjects suffering from depression and see if their symptoms have lessened after a month. You have
eight subjects available. Half of the subjects are to be given the new medication and the other half a
placebo. The names of the eight subjects are given below.
1. Blumenthal
2. Costello
3. Duvall
4. Fan
5. House
6. Long
7. Pavlicova
8. Tang
Using the list of random digits
81507 27102 56027 55892 33063 41842 81868 71035 09001 43367 49497
starting at the beginning of this list and using single-digit labels, you assign the first four subjects
selected to receive the new medication, while the remainder receive the placebo. The subjects assigned
to the placebo are
A) Blumenthal, Costello, Duvall, and Fan.
B) Blumenthal, Costello, House, and Tang.
C) House, Long, Pavlicova, and Tang.
D) Costello, Duvall, Fan, and Long.
E) Blumenthal, House, Pavlicova, and Tang.
Page 9
35. Sickle-cell disease is a painful disorder of the red blood cells that affects mostly blacks in the United
States. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell
disease, a study by the National Institutes of Health gave the drug to 150 sickle-cell sufferers and a
placebo to another 150. The researchers then counted the number of episodes of pain reported by each
subject. The response is
A) the drug hydroxyurea.
B) the 300 people in the study.
C) the presence of sickle-cell disease.
D) the number of red blood cells.
E) the number of episodes of pain.
36. In order to assess the opinion of students at the University of Minnesota on campus snow removal, a
reporter for the student newspaper interviews the first 12 students he meets who are willing to express
their opinion. The method of sampling used is
A) numerical sampling.
B) convenience sampling.
C) voluntary response.
D) a census.
E) simple random sampling.
37. A researcher is interested in the cholesterol levels of adults in the city in which she lives. A free
cholesterol screening program is set up in the downtown area during the lunch hour. Individuals can
walk in and have their cholesterol levels determined for free. One hundred and seventy three people
use the service, and their average cholesterol level is 217.8. The sample obtained is an example of
A) a simple random sample, since the experimenter did not know beforehand which individuals
would come to the screening.
B) a stratified sample of high and low cholesterol individuals.
C) a sample probably containing bias and undercoverage.
D) a biased survey since only people in town during the lunch hour participated.
E) a multistage sample of varying cholesterol levels.
38. In order to take a sample of 90 members of a local gym, I first divide the members into men and
women, and then take a simple random sample of 45 men and a separate simple random sample of 45
women. This is an example of a
A) two-step sample.
B) stratified random sample.
C) double-blind simple random sample.
D) randomized comparative experiment.
E) block design.
Page 10
39. A call-in poll conducted by USA Today concluded that Americans love Donald Trump. USA Today
later reported that 5640 of the 7800 calls for the poll came from the offices owned by one man,
Cincinnati financier Carl Lindner, who is a friend of Donald Trump. The results of this poll are
probably
A) surprising, but reliable since it was conducted by a nationally recognized organization.
B) biased, but only slightly since the sample size was quite large.
C) unbiased because the calls were randomly made at varying times.
D) biased, overstating the popularity of Donald Trump.
E) biased, understating the popularity of Donald Trump.
40. To simulate a basketball player who makes 75% of his free throws, we use the digits 1, 2, and 3 to
correspond to making the free throw and the digit 4 to correspond to missing the free throw. Assume
successive shots are independent and we obtain the following sequence of 10 random digits: 19223
95034
Using these digits, the relative frequency of missing a free throw is
A) 1/10.
B) 1/9.
C) 1/6.
D) 5/10.
E) 5/6.
Use the following to answer questions 41-42:
New varieties of corn with altered amino acid patterns may have higher nutritive value than standard corn,
which is low in the amino acid lysine. An experiment compares two new varieties, called opaque-2 and
floury-2, with normal corn. Corn-soybean meal diets using each type of corn are prepared at three different
protein levels, 12%, 16%, and 20%, giving nine diets in all. Researchers assign 10 one-day-old male chicks to
each diet and record their weight gains after 21 days. The weight gain of the chicks is a measure of the nutritive
value of their diet.
41. Referring to the information above, the factors are
A) variety and protein level.
B) the three levels of protein.
C) the 90 one-day-old male chicks.
D) opaque-2 and floury-2 varieties of corn.
E) age of the chicks and length of time for the experiment.
42. Referring to the information above, the experimental units in this experiment are
A) variety and protein level.
B) the weight gains.
C) the 90 one-day-old male chicks.
D) the three different protein levels; 12%, 16%, and 20%.
E) opaque-2 and floury-2.
Page 11
43. To simulate a single roll of a die, we can use the correspondence 1, 2, 3, 4, 5, and 6 in the table of
random numbers. For two consecutive rolls, we can use the correspondence
A) 11, 22, 33, 44, 55, 66.
B) 11, 12, 13, 14, 15, 16, 21, . . . 26, . . ., 61, 62, . . . 66 for 36 possible outcomes.
C) 1, 2, 3, 4, 5, 6, 7, …, 35, 36 for 36 possible outcomes.
D) A, B, and C are correct.
E) Neither A, B, nor C is correct.
44. A marketing research firm wishes to determine if the adult men in Laramie, Wyoming, would be
interested in a new upscale men's clothing store. From a list of all residential addresses in Laramie, the
firm selects a simple random sample of 100 and mails a brief questionnaire to each. The chance that all
100 homes in a particular neighborhood in Laramie end up being the sample of residential addresses
selected is
A) the same as for any other set of 100 residential addresses.
B) exactly 0. Simple random samples will spread out the addresses selected.
C) reasonably large due to the “cluster” effect.
D) 100 divided by the size of the population of Laramie.
E) large since the population of Laramie is small.
45. In order to assess the opinion of students at the University of Minnesota on campus snow removal, a
reporter for the student newspaper interviews the first 12 students he meets who are willing to express
their opinion. In this case, the sample is
A) all those students favoring prompt snow removal.
B) all students at universities receiving substantial snow.
C) the 12 students interviewed.
D) the students attending school during the semester.
E) all students at the University of Minnesota.
Page 12
46. A recent poll conducted by the student newspaper asked, “Who do you believe will win the Ohio State
Undergraduate Student Government elections?” In order to vote, one had to access the student
newspaper's Web site and record one's vote at the student newspaper's Web page. The results of the
poll were summarized in a graphic similar to the one below.
Total Votes: 24
Based on this information,
A) the results of the survey are unreliable since convenience sampling was used.
B) the results of the survey are likely to be unreliable since the sample size was very small.
C) both A and B are true.
D) Patel and Patel should win because Ohio State University has a large student population.
E) Patel and Patel have such a large majority that, even though there are flaws in the poll, they are
still almost certain to win.
47. Will a fluoride mouthwash used after brushing reduce cavities? Twenty sets of twins were used to
investigate this question. One member of each set of twins used the mouthwash after each brushing; the
other did not. After six months, the difference in the number of cavities of those using the mouthwash
was compared with the number of cavities of those who did not use the mouthwash. This experiment
uses
A) random placebos.
B) double-blinding.
C) double replication.
D) a block design.
E) a matched-pairs design.
48. A public opinion poll in Ohio wants to determine whether registered voters in the state approve of a
measure to ban smoking in all public areas. They select a simple random sample of 50 registered voters
from each county in the state and ask whether they approve or disapprove of the measure. This is an
example of
A) a systematic county sample.
B) a block sample.
C) a multistage sample.
D) a simple random sample.
E) a stratified sample.
Page 13
Use the following to answer questions 49-51:
To simulate a toss of a coin we let the digits 0, 1, 2, 3, and 4 correspond to a head and the digits 5, 6, 7, 8, and 9
correspond to a tail. Consider the following game: We are going to toss the coin until we either get a head or we
get two tails in a row, whichever comes first. If it takes us one toss to get the head we win $2, if it takes us two
tosses we win $1, and if we get two tails in a row we win nothing. Use the following sequence of random digits:
12975 13258 45144
49. The estimated probability of winning nothing is
A) 1/2.
B) 2/11.
C) 2/15.
D) 6/15.
E) 7/11.
50. The estimated probability of winning $2 in this game is
A) 1/4.
B) 5/15.
C) 7/15.
D) 9/15.
E) 7/11.
51. The estimated number of tosses in a single trial of the game is
A) 2.0.
B) 15/9.
C) 15/11.
D) 11/7.
E) 7/11.
52. A study to determine whether or not a football filled with helium traveled farther when kicked than one
filled with air found that, while the football filled with helium went, on average, farther than the one
filled with air, the difference was not statistically significant. The response
A) is the gas, air or helium, with which the football is filled.
B) does not exist without statistical significance.
C) is the number of kickers.
D) is the distance the football traveled.
E) is the number of footballs used.
Use the following to answer questions 53-54:
Researchers wish to determine if a new experimental medication will reduce the symptoms of allergy sufferers
without the side effect of drowsiness. To investigate this question, the researchers give the new medication to
50 adult volunteers who suffer from allergies. Forty-four of these volunteers report a significant reduction in
their allergy symptoms without any drowsiness.
Page 14
53. Referring to the information above, this study could be improved by
A) including people who do not suffer from allergies in the study in order to represent a more diverse
population.
B) repeating the study with only the 44 volunteers who reported a significant reduction in their
allergy symptoms without any drowsiness, and giving them a higher dosage this time.
C) randomly choosing the time of day to administer the experimental medication.
D) using a control group.
E) all of the above.
54. Referring to the information above, the experimental units are
A) the researchers.
B) the 50 adult volunteers.
C) the 44 volunteers who reported a significant reduction in their allergy symptoms without any
drowsiness.
D) the six volunteers who did not report a significant reduction in their allergy symptoms without any
drowsiness.
E) people with allergies
55. A market research company wishes to find out whether the population of students at a university
prefers brand A or brand B of instant coffee. A random sample of students is selected, and each student
is asked first to try brand A and then to try brand B, or vice versa (with the order determined at
random). They then indicate which brand they prefer. This is an example of
A) an experiment.
B) an observational study, not an experiment.
C) a stratified sampling design.
D) a block design.
E) a systematic sampling design.
Use the following to answer questions 56-57:
A group of college students believes that herbal tea has remarkable restorative powers. To test their theory they
make weekly visits to a local nursing home, visiting with residents, talking with them, and serving them herbal
tea. After several months, many of the residents are more cheerful and healthy.
56. The confounding variable in this experiment is
A) the emotional state of the residents.
B) the herbal tea.
C) the time of day the tea was consumed.
D) the visits of the college students.
E) the fact that this is a local nursing home.
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57. The explanatory variable in this experiment is
A) the emotional state of the residents.
B) the herbal tea.
C) the fact that this is a local nursing home.
D) the college students.
E) the residents of the nursing home.
Page 16
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
E
B
C
A
C
D
E
B
D
A
A
A
E
E
A
B
D
A
A
A
D
C
D
E
A
A
E
A
E
C
A
C
B
D
E
B
C
B
D
C
A
C
B
A
C
C
E
E
B
E
Page 17
51.
52.
53.
54.
55.
56.
57.
C
D
D
B
A
D
B
Page 18