Older people who walk quickly live longer explains that researchers in 2005 used measurements of walking
speed from data collected in 1996 from about 500 elderly people. National mortality information enabled the
researchers to check on whether the people were still alive nine years later. They found that 27 percent of
people deemed to walk at a fast speed in 1996 (about 2.5 miles per hour) were dead nine years later.
Meanwhile, 77 percent of those evaluated as walking slowly (less than 1.5 mph) had died, as had 50 percent of
those at medium speed.
What type of study was this?
B) retrospective observational study
C) prospective observational study
D) sample survey
E) anecdotal evidence
Researchers have recently studied the phenomenon of “Chemo brain”, whereby chemotherapy drugs for breast
cancer presumably cause women to experience loss of some cognitive ability.The report also claimed that 15%
of the nation’s 2.4 million female breast cancer survivors remain distracted years after their chemo-therapy
treatment. This result was most likely based on
A) an experiment
B) an observational study
C) anecdotal evidence
Ever since Scrooge in Dickens’ A Christmas Carol blamed his sleep disturbances on “a crumb of cheese”, there
has been a common belief that cheese can cause nightmares. The British Cheese Board carried out a study in
2005 that attempted to dispel such rumors. A group of 200 volunteers were asked to eat 20 grams of cheese
30 minutes before going to sleep each night for a week; afterwards, none of the participants reported having
had nightmares; 72% reported having slept very well every night.The response variable’s type is
The design described is
A) an experiment
B) an observational study
C) a survey
Another possible design would be to survey a large group of people, asking them about their cheese
consumption before bed and about their dreams/nightmares. A weakness of this design is
A) lack of a control group
B) confounding variables
C) lack of realism
Suppose researchers want to test the theory that an apple a day keeps the doctor away, and carry out a study
in which a group of 20 patients has their health assessed initially. They are instructed to eat an apple every
day for a month, after which their health is reassessed to see whether or not it has improved overall.The
design described is
See erotic picture, bet big money, researchers contend reports that “when young men were shown erotic
pictures, they were more likely to make a larger financial gamble than if they were shown a picture of
something scary, such as a snake, or something neutral, such as a stapler...”To summarize their results, the
researchers would compare
Carnegie Mellon researchers recently conducted a study in which they influenced participants’ perceptions of
their wealth by asking a question about annual income in a general survey. The first group was made to feel
poor by asking the individuals to report their income on a scale that began at “less than $100,000” and
increased in $100,000 increments, so that most respondents were in the lowest tier. The second group was
made to feel subjectively wealthier by asking them to report income on a scale that began with “less than
$10,000” and increased in $10,000 increments, so that most respondents were in a middle or upper tier.
“Participants received $5 for taking the survey and then were given the chance to buy up to five scratch-off
lottery tickets. Those in the first group bought an average of 1.27 tickets compared to 0.67 tickets bought by
the second group.”What variable types are involved?
A) both categorical
B) both quantitative
C) one each categorical and quantitative
The New York Times reports: “The older a man is, the more likely he is to father children who develop bipolar
disorder as adults, a large Swedish study reports.Previous studies have found an association between paternal
age and both autism and schizophrenia, but this is the first time a connection with bipolar illness has been
suggested. The study appears in the September issue of The Archives of General Psychiatry.The researchers
examined highly accurate Swedish government health records of more than seven million people with known
biological parents to find 13,428 with bipolar disorder diagnosed at two or more separate hospital admissions.
They matched each case with five controls, people of the same age and sex but without bipolar illness. They
divided the fathers into five-year age categories beginning at 20.After statistically adjusting for the age of the
mother, family history of psychotic disorders, education level and other factors, they found consistently
increasing risk as fathers aged. The highest risk was in fathers 55 and older. For mothers, after adjusting for
the fathers age, they found a statistically significant increase in only the 35 to 39 age group.”Which one of the
following was treated as a response variable?
A) gender of the parent
B) gender of the child
C) age of the parent
D) age of the child
E) whether the child has bipolar disorder
F) whether the child was born in Sweden
“Men with egalitarian attitudes about the role of women in society earn significantly less on average than men
who hold more traditional views about women’s place in the world... The comparisons were based on men and
women working in the same kinds of jobs with the same levels of education and putting in the same number of
hours per week. Men with traditional attitudes about gender roles earned $11,930 more a year than men with
egalitarian views...”What is taken to be the response variable here?
D) kind of job
The Effect of Authority Status on Compliance describes an undergraduate psychology research study which
recruited 29 female college students who were asked to complete a questionnaire. Afterwards, the researcher
requested that they deliver an envelope to a remote part of campus. In some cases the researcher was made
to appear as an authority figure in professional garb with labcoat. In other cases the researcher posed as a
non-authority figure in jeans and a T-shirt. The researchers wanted to see if the students were more likely to
agree to deliver the envelope if the request was made by the authority figure. Their purpose was to explore
the idea that Nazis managed to manipulate people because of their willingness to comply with authority
figures.Authority or non-authority status plays what role here?
A) explanatory variable
B) response variable
C) confounding variable
D) none of the above
A survey reported that 56% of 5,300 business graduate students admitted having cheated.The number 0.56 is
A) a parameter denoted p
a parameter denoted p
C) a statistic denoted p
D a statistic denoted p
A study by the National Coffee Association found that 83% of the cups of coffee consumed by surveyed
Americans were drunk during the morning.The number 0.83 is
A) a statistic denoted p
a statistic denoted p
C) a parameter denoted p
D a parameter denoted p
What is the variable of interest?
A) how much coffee was consumed
B) whether coffee was consumed in the morning
Of 1,007 firearms recovered by a city’s police bureau’s Firearms Tracking Unit in 2007, only 12% had been
reported as stolen.If we use the results to claim that approximately 12% of recovered firearms in the U.S. had
been reported as stolen, there may be bias due to
A) a sample that is not representative of the larger population
B) improperly assessing the variable’s values
The Food and Drug Administration wanted to inspect plants around the world that manufacture drugs to be
exported to the U.S. This stemplot shows the percentage of drug plants that the FDA inspected in ten countries
that export products to the U.S. Stems represent percents and leaves represent tenths of a percent; the
maximum is 12.0 percent.
An alternative display would be a
A) pie chart
C) bar graph
This histogram shows annual per capita spending on bakery products, recorded for 24 U.S. cities in 2006.
How do we denote the mean and standard deviation of this data set?
A and s
μ and σ
C p and p
The shape is
A) very skewed to the left
B) roughly symmetric
C) very skewed to the right
The New York Times reported on the prices of 40 different brands of lipstick. Here is a histogram of the data.
Which one of these is the mean price?
Which one of these is a reasonable guess for the standard deviation, which measures typical distance of prices
from their mean? (No calculations necessary.)
Lengths of newborn babies (in centimeters) are known to be normally distributed with a mean of 50
centimeters and a standard deviation of 5 centimeters.How do we denote the number 5?
Weights in kilograms of boys at the start of first grade are approximately normally distributed with a mean of
25 and a standard deviation of 5.What notation should be used for the number 5?
Prices of wine (by the bottle) for a large distributor are approximately normal with a mean of 44 dollars and a
standard deviation of 14 dollars.A price as high as $100 is
A) extremely unusual
B) somewhat unusual
C) quite common
Census data are available for how male and female workers in a certain city commute. Approximate counts are
shown in this two-way table.
Car Bus/Trolley Total
Men 43,000 11,000 54,000
Women 40,000 16,000 56,000
Total 83,000 27,000 110,000
To summarize the tendency to commute by car for males vs. females, what proportions should be compared?
Researchers at the Cleveland clinic compared mortality rates for a sample of cardiac surgery patients who
received transfusions of fresh blood (less than two weeks old) and those who received older blood (at least
two weeks old). Approximate counts are shown in this two-way table.
Died Survived Total
Fresh Blood 51 2949 3000
Older Blood 84 2916 3000
Total 135 5865 6000
Which patients were more likely to die?
A) those given fresh blood
B) those given older blood
C) both about the same
Cash incentives motivate dieters to enrich themselves described a study that explored the potential of
monetary rewards as an incentive to lose weight. “The researchers designed three groups and randomly
assigned 57 adult participants among them. People in one group entered a daily lottery and won money if they
hit their target weight. Those in the second group invested their own money but lost it if they fell short of their
weight goal. A control group was monitored with monthly weigh-ins. The weight-loss goal was the same for
everyone—16 pounds over 16 weeks...The lottery group earned an average of $272 and lost a mean of 13.1
pounds, with just over half meeting the 16-pound target. The deposit group earned an average of $378 and
lost a mean of 14 pounds, with just under half hitting the goal. But the control group, which earned nothing,
lost a mean of only 3.9 pounds, and only 10.5 percent met the goal.”
One treatment group was quite different from the other two in terms of how much weight was lost; which was
A) the group given an opportunity to win money in a lottery
B) the group who risked losing their own investment
C) the control group (no cash incentive, just monthly weigh-ins)
Boxplots are shown below for prices of English Sheepdogs and Yorkshire Terriers listed in the classified ads.
The most noticeable difference between the two distributions is their
A sample of students taking statistics were asked to predict their first exam score as a percentage. This boxplot
shows results for the female and male students.
The mean prediction for females was about two points higher than that for males. Which of these would be
more convincing evidence that mean predicted exam score would be higher for populations of male and female
students in similar circumstances, not just for the samples?
A) if 10 each males and females were sampled
B) if 20 each males and females were sampled
C) if 200 each males and females were sampled
D) sample size is irrelevant here
Here are side-by-side boxplots for prices per bottle of samples of two types of wine— Cabernet and
25 is a reasonable guess for
A) median price of Cabernet
B) third quartile for Chardonnay
C) both (a) and (b)
D) neither (a) nor (b)
A newspaper reported on 2007-2008 pays for college presidents at public universities in Pennsylvania, private
colleges in a particular county (Allegheny), and some other private colleges in Pennsylvania. The boxplot below
displays the pays, where units are thousands of dollars.
Which of these is most similar for the three groups?
C) standard deviation
How would the standard deviation for other private colleges in Pennsylvania (box on the right) compare to the
standard deviation for public universities in Pennsylvania (box on the left)?
A) much less
B) almost the same, but a bit less
C) almost the same, but a bit more
D) much more
A drug company listed prices of brand-name drugs, along with the accompanying generic substitute. Generic
price was regressed on brand-name price, and a scatterplot was obtained.
How can we summarize the shapes of the individual distributions?
A) brand and generic prices both left-skewed/low outliers
B) brand and generic prices both right-skewed/high outliers
C) brand prices left-skewed/low outliers and generic prices right-skewed/high outliers
D) brand prices right-skewed/high outliers and generic prices left-skewed/low outliers
Which one of these is the standard deviation for generic prices?
Note that the correlation is the positive or negative square root of R - Sq. The relationship between brand and
generic prices is
A) strong and negative
B) moderate and negative
C) weak and negative
D) weak and positive
E) moderate and positive
F) strong and positive
The relationship between average reading and average writing SAT score was examined for a sample of 19
The relationship is apparently
A) weak and negative
B) strong and negative
C) weak and positive
D) strong and positive
A student looked at rent charged and size (from 1 to 4 bedrooms) of a sample of off-campus apartments.
The individual distribution for number of bedrooms has what shape?
D) cannot be determined
If the point at the far right of the scatterplot had not been included, the regression line would be
B) less steep
C) about the same
The relationship between total district budget and charter school allotment (both in millions of dollars) was
examined for a sample of 6 school districts.
If roles were reversed, so that charter school allotment were the explanatory variable, which of these would be
A) strength of the relationship
B) equation of the regression line
A recent newspaper article described Republicans’ reactions to accusations that House Majority Leader Tom
DeLay unethically accepted travel money from lobbyists. The article published a list of trips between January of
2000 and March of 2005 financed by private interests for a certain state’s members of Congress, including the
length of travel (in days) and the dollar amount paid. A scatterplot has been constructed from the data, along
with output for regression of dollar amount paid on trip length.
If dollars had been entered as the explanatory variable and length of travel the response, how would the
correlation be affected?
C) stay the same
The scatterplot shows
A) obvious outliers
B) obvious influential observations
The output and scatterplot are for the regression of average percentage yield on certificates of deposit for
twelve months versus six months at a sample of 6 area banks.
How do we denote the number 0.44?
The regression output and scatterplot are for average commercial insurance payments, in thousands of dollars,
made to ten hospitals in a certain city for heart valve surgery vs. coronary bypass surgery.
Which of these is your best guess for the correlation r?
Considering its position on the scatterplot and the fact that its residual is +3.2, the hospital that averaged 35
thousand for coronary bypass surgery and 54 thousand for valve surgery could be considered an
B) influential observation
Regression output and a scatterplot are shown for overall rankings of football quarterbacks in a popular video
game, versus their QB vision ratings. (Each quarterback is given a field of vision, represented by a cone of light
on the field that highlights exactly what he can see.)
How do we denote the number 44?
Regression output and a scatterplot are shown for purchase price and rent for the 22 streets on a Monopoly
In fact, the rent for landing on Boardwalk is $50. The regression equation
A) underpredicted the rent
B) overpredicted the rent
The scatterplot and regression output below are for numbers of students enrolled in a variety of courses in a
region’s colleges and universities, and the percentages of students in those courses receiving F or W grades.
College Writing at a certain community college had 911 students enrolled, and 25% of students receiving F’s or
W’s. Which of these would be likely to occur if this point were removed from the regression?
A) the line would remain roughly unchanged
B) the slope of the line would be steeper
C) the slope of the line would be shallower
If we reversed roles, taking failure rate as the explanatory variable and enrollment as the response, which of
these would change?
A) correlation r
B) equation of the regression line
The Defense Department’s mass mental health screening of service members returning from ground combat
operations from May of 2003 to April of 2004 looked at where the soldiers had served, and whether the
soldiers accessed outpatient mental health services upon their return.
Mental Health Service No Mental Health Service Total
Iraq 77,700 144,300 222,000
Other Location 17,160 60,840 78,000
Total 94,860 205,140 300,000
Apparently, location served and accessing mental health services are
Researchers at Carnegie Mellon University wanted to see if people’s desire for variety in snacks was more
pronounced when two different snacks were offered simultaneously, as opposed to sequentially. They
reasoned as follows: “If you have just eaten an orange it might well make an immediate second orange less
appealing, but it will probably have little effect on the pleasure of an orange eaten tomorrow.” This table
shows counts of subjects taking two of the same kind of snack, and those taking one each of two different
kinds of snack, when offered a variety of snacks under two conditions: some subjects were offered the snacks
sequentially, one a week for two weeks, and others were allowed to take two snacks simultaneously at one
Observed Chose Same Snacks Chose Different Snacks Total
Sequential Choice 20 20 40
Simultaneous Choice 10 50 60
Total 30 70 100
Does the table seem to provide evidence of a relationship in general between whether snacks are offered
simultaneously or sequentially and whether the someone chooses both the same or two different?
Researchers carried out a study on small children, where they pretended to go shopping together and then
recorded the imaginary purchases. Of interest were whether or not the children “bought” (pretended to buy
cigarettes, and whether or not the children’s parents smoked. Results are shown in the table below.
Bought Cigarettes Didn't Buy Cigarettes Total
Parents Smoke 18 12 30
Parents Don't Smoke 18 72 90
Total 36 84 120
How did the probability of “buying” cigarettes compare for the two groups of children?
A) Children were twice as likely to buy cigarettes if their parents smoked.
B) Children were half as likely to buy cigarettes if their parents smoked.
C) Children were just as likely to buy cigarettes if their parents smoked.
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