Review
 In
one study on the effect of niacin on cholesterol level, 100
subjects who acknowledged being long-time niacin takers had
their cholesterol levels compared with those of 100 people
who had never taken niacin. In a second study, 50 subjects
were randomly chosen to receive niacin and 50 were chosen
to receive a placebo.
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A) The first study was a controlled experiment, while the second
was an observational study.
B) The first study was an observational study, while the second was
a controlled experiment.
C) Both studies were controlled experiments.
D) Both studies were observational studies.

Each of the 29 NBA teams has 12 players. A sample of 58 players is
to be chosen as follows. Each team will be asked to place 12
cards with their players names into a hat and randomly draw out
two names. The two names from each team will be combined to
make up the sample. Will this method result in a SRS of the
players?
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A) Yes, because each player has the same chance of being selected.
B) Yes, because each team is equally represented.
C) Yes, because this is an example of stratified sampling, which is a
special case of SRS.
D) No, because the teams are not chosen randomly.
E) No, because not each group of players has the same chance of being
selected.
A
consumer product agency tests miles per gallon for a
sample of automobiles using each of four different octane of
gasoline. Which of the following is true?
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A) There are four explanatory variables and one response variable.
B) There is one explanatory variable with four response variables.
C) Miles per gallon is the only explanatory variable, but there are
four response variables.
D) There are four levels of a single explanatory variable.
E) Each explanatory level has an associated level of response.
 Your
company has developed a new treatment for acne.
You think men and women might react differently to the
medication, so you separate them into two groups. Then
the men are randomly assigned into two groups and the
women are randomly assigned into two groups. One of the
two groups is given the medicine, the other is given a
placebo. The basic design of this study is:
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A) completely randomized
B) randomized block, blocked by gender
C) completely randomized, stratified by gender
D) randomized block, blocked by gender and type of medication
E) a matched pairs design
A

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double-blind design is important in an experiment because:
A) There is a natural tendency for subjects in an experiment to
want to please the researcher.
B) It helps control for the placebo effect.
C) Evaluators of the responses in a study can influence the
outcomes if they know which treatment the subject received.
D) Subjects in a study might react different if they knew which
treatment they were receiving.
E) All of the above reasons are valid.

1. B


2. E


This experiment has one factor (explanatory variable) of gasoline,
with four levels of octane.
4. B


Since two players were chosen from each of the 29 teams, this is a
stratified sample, not a SRS. For this to be a simple random
sample, all of the players would have been in one really big hat.
Part of the definition of SRS means that all subgroups have the same
chance to be selected.
3. D


In the first study, the subjects were already niacin users. In the
second study, the treatment of niacin was randomly assigned
(imposed)to the subjects.
Since you think that men and women will react differently, you
separated your subjects by gender first. This is an example of
blocking. An experiment that uses blocking is called a randomized
block design.
5. E

Double-blinding is used in experiments so that neither the subject
nor the evaluator will inadvertently affect the results of the study
because they knew which treatment was received.
A
school committee member is lobbying for an increase in the
gasoline tax to support the county school system. The local
newspaper conducted a survey of county residents to assess
their support for such an increase. What is the population of
interest here?
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A)
B)
C)
D)
E)
All school aged children
All county residents
All county residents with school aged children
All county residents with children in the school system
All county school system teachers
 An
experiment was designed to test the effect of 3 different
types of paints on the durability of wooden toys. Since boys
and girls tend to play differently with toys, a randomly
selected group of children was divided into 2 groups by
gender. Which of the following statements about this
experiment is true?
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A) Type of paint is a blocking factor
B) Gender is a blocking factor
C) This is a completely randomized design
D) This is a matched pairs design in which one boy and one girl are
matched to form a pair.
 Which
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A)
B)
C)
D)
E)
of the following is not a source of bias in a survey?
non-response
wording of the question
voluntary response
use of a telephone survey
all are sources of bias
 Which
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of the following is not a valid sampling design?
A) Number every member of the population and select 100
randomly chosen members
B) Divide a population by gender and select 50 individuals
randomly from each group
C) Select every 20th person, starting at a random point
D) select five homerooms at random from all the homerooms in a
large high school
E) All of these are valid
 Characteristics
of a population are called ______________,
while those of a sample are called _____________.
A.
B.
C.
D.
E.
Statistics; measures
Parameters; statistics
Statistics; variables
Statistics; parameters
None of these

1. B


2. B


Non-response is when someone that was chosen for our survey
cannot be contacted or refuses to respond. Sometimes in a survey,
a question will not be worded in a fair manner and will have a
“leading statement” that affects the responses. Voluntary response
surveys put out a general call and the people that choose to respond
are then counted. This type of survey often over-represents people
with strong opinions. The telephone issue is becoming more of a
problem as the younger generations tend to use their cell phones
more and more as their primary phone number.
4. E


Since you think that boys and girls will play differently with the toys
you first separate by gender. So gender is the blocking factor.
3. E


The population of interest is who you are interested in learning
more about. In this case, “The local newspaper conducted a survey
of county residents…”, so they are interested in learning more
about the county residents.
All of these use random sampling methods.
5. B

This is the definition of parameters and statistics.
 The
control group in an experiment should be designed to
receive:
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A) the opposite of the experiences afforded the experimental
group.
B) The experiences afforded the experimental group except for the
treatment under experimentation.
C) The experiences afforded the experimental group except for
receiving the treatment at random.
D) The experiences which constitute an absence of the experiences
received by the experimental group.
 Which
of the following is NOT true of simple random
sampling?
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A) Whether or not a sample is random cannot be told from
inspection of the sample.
B) Characteristics of a random sample may differ widely from
characteristics of its population.
C) A sample must be reasonably large to be considered a random
sample.
D) Every element and every set of elements in the population must
be given an equal chance for inclusion in the sample.
 Of
A-D, which is not a critical part of designing a good
experiment?
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A) Control of known sources of variability
B) Random selection of subjects
C) Random assignments of subjects to treatments
D) Replication of the experiment on a sufficient number of
subjects
E) All of these are important
A
survey records many variables of interest to the
researchers conducting the survey. Which of the following
variables, from a survey conducted by the U.S. postal
service, is categorical?
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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
 Hoping
to get information that would allow them to negotiate
new rates with their advertisers, Natural Health magazine
phoned a random sample of 600 subscribers. 64% of those polled
said they use nutritional supplements. Which is true?
The population of interest is the people who read this magazine.
II. “64%” is not a statistic; it’s the parameter of interest
III. This sampling design should provide the company with a reasonably
accurate estimate of the percentage of all subscribers who use
supplements.
A) I only
B) I and II only
C) I and III only
D) II and III only E) I, II, and III
I.

1. B
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2. C

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When designing an experiment, we cannot randomly choose
subjects to experiment on – that’s unethical! The randomization
comes from assigning treatments to the people that volunteered to
be in the study.
4. A
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A random sample does not need to be large to be random. The
randomness comes from the method used to select the subjects.
3. B
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The control group should be roughly the same as the experimental
group EXCEPT for the treatment received.
The other options are quantitative variables – numerical values that
you could measure and do math on.
5. C

The magazine was interested in finding out information from their
readers. The “64%” is a value that refers to the 600 people that
were part of the sample and therefore the 64% is a statistic. The
parameter would be the true (unknown) percent of all subscribers
that use supplements. Since this sample was taken using random
methods, it should be fairly reliable. There may be some minor
issues with people not answering the phone, etc. Probably not
enough to completely throw off the results.
A
researcher wants to compare the performance of three
types of pain relievers in volunteers suffering from arthritis.
Because people of different ages may react differently to
medication, the subjects are split into two groups: under 60
and over 60. Subjects in each group are randomly assigned
to take one of the medications. Twenty minutes later they
rate their levels of pain. This experiment…
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A) is completely randomized.
B) uses matched pairs.
C) has two factors, medication and age.
D) has one factor (medication) blocked by age.
E) has one factor (age) blocked by type of medication.
A
Male
Female
Democrat
300
600
Republican
500
300
Other
200
100
review of voter registration records in
a small town yielded the following table
of the number of males and females
registered as Democrat, Republican, or
some other affiliation.
The proportion of registered Democrats
who are male is:
A)
 B)
 C)
 D)

300
.33
.30
.15
Male
Female
Democrat
300
600
Republican
500
300
Other
200
100
 Using
the same table, what is the marginal
distribution of political party?
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A) Female: 33%
B) Democrat: 45%
Other: 15%
C) Democrat: 30%
Other: 20%
D) Female: 50%
Male: 67%
Republican: 40%
Republican: 50%
Male: 50%
 1.
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 2.
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 3.
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D
This study split people by age because they thought age would make a
difference. This is called blocking. The experiment was testing
medication, which is the factor being studied.
B
We are limiting ourselves to just the registered Democrats (900 total) and
want to know the proportion of males in that group (300 out of 900).
B
Marginal distributions look at the total percentages. We want the total
percent of Democrats, Republicans, and Other.