Multiple Choice Identify the
choice that best completes the statement or answers the question.
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1.
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A survey typically records many variables of interest to the researchers
involved. Below are some of the variables from a survey conducted by the U.S. Postal
Service. Which of the variables is categorical?
a. | County of residence | b. | Number of people, both adults and children,
living in the household | c. | Total household income, before taxes, in
1993 | d. | Age of respondent | e. | Number of rooms in the
dwelling |
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2.
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The histogram below shows the length (in minutes) of 140 songs recorded by the
band Wilco. Which of the following descriptions best fits
this distribution?
a. | Skewed right, centered at about 8, with several high outliers. | b. | Skewed left,
centered at about 8, with several high outliers. | c. | Skewed right, centered at about 4.5, with
several high outliers. | d. | Skewed left, centered at about 4.5, with
several high outliers. | e. | Skewed left, centered at about 3.5, with
several high outliers. |
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3.
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Which of the following statements is true?
a. | In a distribution that is skewed right, the median is larger than the
mean. | b. | Fifty percent of the scores in a distribution are between the first and third
quartile. | c. | The third quartile of a distribution is always greater than the
mean. | d. | The median of a distribution is always greater than the mean. | e. | The range of a
distribution is typically smaller than the interquartile range. |
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4.
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The first sentence in Henry James’s novel The Turn of the Screw has
62 words. The five number summary for the lengths of those words is 1, 2, 3.5, 6,
12. According to the 1.5 x IQR rule for identifying outliers, does this distribution have any
outliers?
a. | No, there are no outliers. | b. | Yes, there is at least on high outlier but no
low outliers. | c. | Yes, there is at least one low outliers, but no high outliers. | d. | Yes, there is at
least one high and one low outlier. | e. | There is not enough information given to
determine if there are any outliers. |
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5.
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For the density curve below, which of the following is true?
a. | The median is 0.5. | b. | The median is larger than
0.5. | c. | The density curve is skewed right. | d. | The density curve is
Normal. | e. | The density curve is symmetric. |
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6.
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The distribution of household incomes in a small town is strongly skewed to the
right. The mean income is $42,000 and the standard deviation is $24,000. The Ames
family’s household income is $60,000. The z-score for the Ames family’s
income is
a. | –0.75 | b. | 0.3 | c. | 0.75 | d. | 0.86 | e. | None of these,
because z-score cannot be used unless the distribution is
Normal. |
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Scenario 2-1
A sample was taken of the salaries of 20 employees of
a large company. The following are the salaries (in thousands of dollars) for this year.
For convenience, the data are ordered. | 28 | 31 | 34 | 35 | 37 | 41 | 42 | 42 | 42 | 47 | | 49 | 51 | 52 | 52 | 60 | 61 | 67 | 72 | 75 | 77 | | | | | | | | | | | |
Suppose
each employee in the company receives a $3,000 raise for next year (each employee's salary is
increased by $3,000).
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7.
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Use Scenario 2-1. The mean salary for the employees will
a. | be unchanged. | b. | increase by $3,000. | c. | be multiplied by
$3,000. | d. | increase by . | e. | increase by
$150. |
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8.
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Using the standard Normal distribution tables, the area under the standard
Normal curve corresponding to Z < 1.1 is
a. | 0.1357. | b. | 0.2704. | c. | 0.8413. | d. | 0.8438. | e. | 0.8643. |
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9.
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The scores on a university examination are Normally distributed with a mean of
62 and a standard deviation of 11. If the bottom 5% of students will fail the course, what is the
lowest mark that a student can have and still be awarded a passing grade?
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Scenario 3-3
Consider the following scatterplot, which describes
the relationship between stopping distance (in feet) and air temperature (in degrees Centigrade) for
a certain 2,000-pound car travelling 40 mph.
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10.
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Use Scenario 3-3. The correlation between temperature and stopping
distance
a. | is approximately 0.9. | b. | is approximately 0.6. | c. | is approximately
0.0. | d. | is approximately -0.6. | e. | cannot be calculated, because some of the
x values are negative. |
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Scenario 3-5
In a statistics
course a linear regression equation was computed to predict the final exam score from the score on
the first test. The equation of the least-squares regression line was where
represents the predicted final exam score and x is the score on the first
exam.
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11.
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Use Scenario 3-5. Suppose Joe scores a 90 on the first exam. What would be
the predicted value of his score on the final exam?
a. | 91 | b. | 90 | c. | 89 | d. | 81 | e. | Cannot be determined
from the information given. We also need to know the
correlation. |
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12.
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Use Scenario 3-8. The equation of the least-squares regression line
is
a. | = –142.74 + 39.25
(Length) | b. | = 39.25 – 142.74 (Length) | c. | =
25.55 + 5.392 (Length) | d. | = 25.55 + 5.392
(Eggs) | e. | = –142.74 + 39.25
(Eggs) |
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Scenario 4-1
A sportswriter wants to know how strongly Lafayette
residents support the local minor league baseball team, the Lafayette Leopards. She stands outside
the stadium before a game and interviews the first 20 people who enter the stadium.
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13.
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Use Scenario 4-1. The intended population for this survey is
a. | all residents of Lafayette. | b. | all Leopard fans. | c. | all people attending
the game the day the survey was conducted. | d. | the 20 people who gave the sportswriter their
opinion. | e. | all American adults. |
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14.
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Use Scenario 4-1. The sample for the survey is
a. | all residents of Lafayette. | b. | all Leopard fans. | c. | all people attending
the game the day the survey was conducted. | d. | the 20 people who gave the sportswriter their
opinion. | e. | the sportswriter. |
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15.
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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. | a census | b. | a cluster sample | c. | a voluntary response
sample | d. | a convenience sample | e. | a simple random
sample |
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Scenario 4-3
We wish to choose a simple random sample of size
three from the following employees of a small company. To do this, we will use the numerical
labels attached to the names below. 1. Bechhofer | 4. Kesten | 7. Taylor | 2. Brown | 5. Kiefer | 8.
Wald | 3. Ito | 6.
Spitzer | 9. Weiss | | | |
We will also use the
following list of random digits, reading the list from left to right, starting at the beginning of
the list. 11793 20495 05907 11384 44982 20751 27498
12009 45287 71753 98236 66419 84533
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16.
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Use Scenario 4-3. The simple random sample is
a. | 117. | b. | Bechhofer, Bechhofer again, and
Taylor. | c. | Bechhofer, Taylor, Weiss. | d. | Kesten, Kiefer, Taylor. | e. | Taylor, Weiss,
Ito. |
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Scenario 4-4
You want to take an SRS of 50 of the 816 students who
live in a dormitory on campus. You label the students 001 to 816 in alphabetical order. In the table
of random digits you read the entries 95592 94007
69769 33547 72450 16632 81194 14873
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17.
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Use Scenario 4-4. The first three students in your sample have labels
a. | 955, 929, 400. | b. | 400, 769, 769. | c. | 559, 294,
007. | d. | 929, 400, 769. | e. | 400, 769, 335. |
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18.
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A public opinion poll in Ohio wants to determine whether or not registered
voters in the state approve of a measure to ban smoking in all public areas. They select a
simple random sample of fifty 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 random sample. | b. | stratified random sample. | c. | multistage
sample. | d. | simple random sample. | e. | cluster sample. |
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19.
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To determine the proportion of each color of Peanut Butter M&M, you buy 10
1.69 ounce packages and count how many there are of each color. This is an example of
a. | simple random sampling | b. | cluster sampling | c. | multistage
sampling | d. | stratified random sampling | e. | systematic random
sampling |
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20.
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Frequently, telephone poll-takers call near dinner time—between 6 pm and 7
pm—because most people are at home them. This is an effort to avoid
a. | voluntary response bias. | b. | calling people after they have gone to
bed. | c. | a convenience sample. | d. | nonresponse. | e. | response
bias. |
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21.
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The Bradley effect is a theory proposed to explain observed discrepancies
between voter opinion polls and election outcomes in some elections where a white candidate and a
non-white candidate run against each other. The theory proposes that some voters tend to tell
pollsters that they are undecided or likely to vote for a non-white candidate, and yet, on election
day, vote for the white opponent. This is an example of
a. | voluntary response bias. | b. | bias resulting from question
wording. | c. | undercoverage. | d. | nonresponse. | e. | response
bias. |
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Scenario 4-5
In order to assess the effects of exercise on
reducing cholesterol, a researcher took a random sample of fifty people from a local gym who
exercised regularly and another random sample of fifty people from the surrounding community who did
not exercise regularly. They all 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 or not subjects exercised regularly.
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22.
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Use Scenario 4-5. This is a(n)
a. | observational study. | b. | experiment, but not a double blind
experiment. | c. | double blind experiment. | d. | matched pairs experiment. | e. | block
design. |
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23.
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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 one is asked to try brand A first and then brand B (or vice versa, with the order
determined at random). They then indicate which brand they prefer. The response variable
is
a. | whether brand A or B is tried first. | b. | which brand they prefer. | c. | coffee. | d. | the identity of the
student. | e. | none of these. |
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24.
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The most important advantage of experiments over observational studies is
that
a. | experiments are usually easier to carry out. | b. | experiments can give
better evidence of causation. | c. | confounding cannot happen in
experiments. | d. | an observational study cannot have a response variable. | e. | observational
studies cannot use random samples. |
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25.
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Use Scenario 4-7. The brand of pellets is
a. | a parameter. | b. | the response variable. | c. | the explanatory
variable. | d. | the placebo effect. | e. | a dependent
variable. |
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Scenario 4-8
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 randomly assigned 100 adult volunteers who suffer from
allergies to two groups. They gave the new medication to the subjects in one group and an
existing medication to the subjects in the other group. Forty-four percent of those in the
treatment group and 28% of those in the control group reported a significant reduction in their
allergy symptoms without any drowsiness.
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26.
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Use Scenarion 4-8. The experimental units are the
a. | researchers. | b. | 100 adult volunteers. | c. | all the volunteers
who reported a significant reduction in their allergy symptoms without any
drowsiness. | d. | all the volunteers who did not report a significant reduction in their allergy
symptoms without any drowsiness. | e. | pills containing the new experimental
medication. |
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27.
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The owner of a chain of supermarkets notices that there is a positive
correlation between the sales of beer and the sales of ice cream over the course of the previous
year. During seasons when sales of beer were above average, sales of ice cream also tended to
be above average. Likewise, during seasons when sales of beer were below average, sales of ice
cream also tended to be below average. Which of the following would be a valid conclusion from
these facts?
a. | Sales records must be in error. There should be no association between beer and
ice cream sales. | b. | Evidently, for a significant proportion of customers of these supermarkets, drinking
beer causes a desire for ice cream or eating ice cream causes a thirst for beer. | c. | A scatterplot of
monthly ice cream sales versus monthly beer sales would show that a straight line describes the
pattern in the plot, but it would have to be a horizontal line. | d. | It is likely that
sales of both beer and ice cream are confounded with another variable, such as seasonal variation in
temperature. | e. | There is a clear, negative association between beer sales and ice cream
sales. |
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28.
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The principle reason for the use of controls in designing
experiments is that it
a. | distinguishes a treatment effect from the effects of confounding
variables. | b. | allows double-blinding. | c. | reduces sampling
variability. | d. | creates approximately equal groups for comparison. | e. | eliminates the
placebo effect. |
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29.
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A double-blind experiment was conducted to evaluate the effectiveness of the
Salk polio vaccine. The purpose of keeping the diagnosing physicians ignorant of the treatment status
of the experimental subjects was to
a. | eliminate grounds for malpractice suits. | b. | ensure that subjects
were randomly assigned to treatments. | c. | eliminate a possible source of
bias. | d. | make sure nobody is harmed. | e. | prevent stratification of the
experiment. |
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30.
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In comparative trials in medicine, the placebo effect and subconscious bias on
the part of the physicians evaluating treatment outcomes can be avoided by using
a. | the double-blind technique. | b. | randomized complete block
designs. | c. | response variables. | d. | stratified random samples. | e. | all of the
above. |
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31.
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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 are to be given 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. A block design is appropriate in
this experiment if
a. | we want to be able to compare effects on energy level in men and
women. | b. | we believe men and women will respond differently to treatments. | c. | gender equity is an
important legal consideration in this study. | d. | we want the conclusions to apply equally to men
and women. | e. | all of the above. |
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