Stats Final

Front 1

A study compared the response variable life length for left-handed and right-handed people. Based on this information, the study must have been

Back 1

an observational study

Front 2

A pollster reported that 30% of voters approve of a certain politician's job performance with a margin of error of 10%. An interval that "almost certainly" contains the true percentage of all voters who approve of this politician's job performance is

Back 2

20% to 40%.

Front 3

Suppose the subjects in a study were obtained by inviting the first 50 people who entered a particular restaurant when it opened one morning to fill out a questionnaire. This information suggests that the study may have problems relative to

Back 3

Component 3 (individuals or objects studied).

Front 4

Suppose that a study concluded that it was safe for children to take antidepressants. If that study were funded by a pharmaceutical company that manufactures antidepressants, we might be concerned about bias relative to

Back 4

Component 1 (source).

Front 5

A survey may be biased if it is conducted immediately following a major event. Of the Seven Critical Components, this form of bias would be classified under

Back 5

Component 5 (setting)

Front 6

A survey question asked, "Have you ever been convicted of a crime?" A number of respondents had been convicted of minor traffic violations (and had no other convictions). Of those, some answered "yes," and others answered "no." This source of bias would be classified under

Back 6

Component 4 (measurements).

Front 7

Suppose that a study found that smokers who used a nicotine patch were much more likely to quit smoking than smokers who used a placebo patch. Suppose that the nicotine patch group consisted of smokers who had been diagnosed with lung cancer, and the placebo group consisted of smokers who had no serious medical problems. Based on this information, we should be concerned about bias relative to

Back 7

Component 6 (extraneous differences)

Front 8

Suppose that a survey asked, "Which fast-food restaurant do you think of when you think of great food?" and was conducted by uniformed McDonald's employees going door to door to interview subjects. Based on this information, we should be concerned about bias relative to

Back 8

Component 2 (researchers).

Front 9

Suppose that a study was designed to compare the pulse rates of men and women. If the men studied were all over the age of 40 and the women studied were all under the age of 20, then we should be concerned about possible bias relative to

Back 9

Component 6 (extraneous differences).

Front 10

Which of the following will produce a representative sample of University of Missouri students?

A. randomly selected sample of 100 journalism majors

B. randomly selected sample of 50 journalism majors

C. randomly selected sample of 100 engineering majors

D. randomly selected sample of 500 biology majors

E. None of the above choices represent a suitable response.

Back 10

E

Front 11

A marriage counselor is currently working with 20 couples. She has on her desk four lists: a list of the 20 couples; a list of the 20 husbands; a list of the 20 wives; and a list of the 40 people. For each question, identify the sampling plan used to select the sample of people.

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Back 11

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Front 12

The counselor randomly selects 12 people from the list of the 40 people

Back 12

simple random sample

Front 13

The counselor randomly selects three couples from the list of 20 couples and includes the six people who were in one of the selected couples in her sample.

Back 13

cluster sample

Front 14

The counselor randomly selects five husbands from the list of 20 husbands and then randomly selects five wives from the list of 20 wives. The sample includes the ten people who were selected.

Back 14

stratified random sample

Front 15

The counselor selects the people who are listed 10th, 20th, 30th, and 40th on the list of the 40 people.

Back 15

systematic sample

Front 16

Suppose that a survey presented subjects with a statement and then asked them to describe their feelings with one of three choices: "agree," "neutral," or "disagree." The responses to this survey would form

Back 16

a categorical variable.

Front 17

The number of times that a student dines in a restaurant during a particular week is an example of

Back 17

a discrete measurement variable

Front 18

The height of a building is an example of

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a continuous measurement variable.

Front 19

A high school basketball coach always reports the heights of his players as being two inches taller than the player's actual height. As a measure of a player's actual height, the height reported by the coach is

Back 19

reliable but not valid.

Front 20

A sample of 64 students showed 25 were not registered to vote. The margin of error in using the sample proportion to estimate to population proportion is (plus or minus)

Back 20

12.5%.

Front 21

A volunteer sample

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cannot be generalized to any meaningful population.

Front 22

A sample showed that 50% of people surveyed favored a certain constitutional amendment and reported a margin of error of plus or minus 10%. An interval that "almost certainly" will contain the true percentage of the whole population who favor this constitutional amendment is

Back 22

40% to 60%

Front 23

The margin of error serves as a measure of

Back 23

sampling error.

Front 24

The variable "number of classes attended" by an undergraduate for one week is

Back 24

a discrete measurement variable.

Front 25

A systematic prejudice in one direction is called

Back 25

a bias.

Front 26

An experiment was conducted in order to compare blood pressures for heart patients who had taken a new drug with those who had taken an older drug. The explanatory variable in this experiment is

Back 26

the drug (new or older).

Front 27

If the way that the explanatory variable affects the response variable depends on the value of a third variable, then we say that the explanatory variable and the third variable

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interact.

Front 28

A study in which subjects are randomly assigned to groups is an example of

Back 28

an experiment.

Front 29

A doctor claims to be able to cure migraine headaches. If a questionnaire were administered to each patient the doctor claims to have cured, we would classify this as

Back 29

a case study.

Front 30

Subjects in an experiment may be blinded in order to

Back 30

monitor the placebo effect.

Front 31

The Hawthorne effect is

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the tendency of subjects to respond differently than they normally would, just because they are in an experiment

Front 32

A study compared the blood pressures of smokers and non-smokers. It concluded that smokers have higher blood pressures than non-smokers. Based on this information, this study must have been

Back 32

an observational study.

Front 33

Suppose a study compared grade-point averages for sophomores and seniors. In this context, classification (sophomore or senior) is

Back 33

the explanatory variable.

Front 34

Suppose a study compared resting pulse rates for college athletes and non-athletes. In this context, resting pulse rate is

Back 34

the response variable.

Front 35

Participants in a study were told to administer ever-increasing electrical shocks to another subject who writhed in pain and begged for mercy. (Unbeknownst to the participants, the subject being shocked was a cohort and was not actually harmed.) When asked why he continued to shock the subject, one participant remarked, "I was in a psychology experiment, so I knew I could not really be harming the guy." It appears that this is an example of

Back 35

the Hawthorne effect.

Front 36

Suppose that a study were designed to compare time until pain relief for two pain relievers (1 and 2). If all of the subjects in group 1 were men and all of the subjects in group 2 were women, then the variables pain reliever (1 or 2) and gender (male or female) are

Back 36

confounded.

Front 37

Suppose that a study were designed to compare time until pain relief for two pain relievers (1 and 2). Group 1 consisted of 25 men and 25 women, who were selected at random, and group 2 consisted of a separate group of 25 men and 25 women, who were also selected at random. The results showed that, for men, pain reliever 1 worked the fastest, while, for women, pain reliever 2 worked the fastest. This information suggests that pain reliever (1 or 2) and gender (male or female) are

Back 37

interacting variables.

Front 38

The numbers of pencils contained in the desks of four randomly selected college professors were: 0, 4, 7, and 9. Note that big sigma x= 20 and big sigma x^2= 146

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Back 38

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Front 39

What is the sample mean?

Back 39

5

Front 40

What is the sample standard deviation?

Back 40

3.916

Front 41

What is the sample median?

Back 41

5.5

Front 42

What is the sample range?

Back 42

9

Front 43

For six students, the amount of television each watched last week (in hours) was: 3, 3, 6, 10, 12, and 14.

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Back 43

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Front 44

(Big sigma x)^2

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2,304

Front 45

Big sigma x^2

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494

Front 46

What is the upper quartile (QU)?

Back 46

12

Front 47

What is the mode?

Back 47

3

Front 48

On Tuesday of last week, a sample of three students was asked, "How many classes did you attend yesterday?" The responses were: 0, 2, and 4.

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Back 48

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Front 49

What is the sample variance?

Back 49

4

Front 50

This data set is

Back 50

symmetric.

Front 51

What is the sample range?

Back 51

4

Front 52

The five-number summary for a data set is: 0, 10, 20, 50, 60. What is the interquartile range?

Back 52

40

Front 53

Suppose that the amounts of money that college students earned last summer had a mean of $3,500, a standard deviation of $500, and a median of $2,900. What does this tell us?

Back 53

The data set is skewed to the right.

Front 54

Suppose that the speeds of pitches thrown during a baseball game approximately follow a bell-shaped (normal) frequency curve with a mean of 90 mph and a standard deviation of 4 mph.

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Back 54

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Front 55

What is the z-score for the speed of a 96 mph pitch?

Back 55

1.50

Front 56

If the z-score for a pitch was –2.5, how fast was that pitch?

Back 56

80 mph

Front 57

According to the Empirical Rule, approximately 95% of pitches are between __________ and __________ mph.

Back 57

82 and 98

Front 58

According to the Empirical Rule, approximately __________ of pitches are between 86 and 94 mph.

Back 58

68%

Front 59

For a population that has a bell-shaped (normal) frequency curve, 16% of the population will have a z-score larger than

Back 59

1.00.

Front 60

The Empirical Rule may be applied to

Back 60

a population that is bell-shaped (normal).

Front 61

The lengths of baseball games follow a frequency curve that is approximately bell-shaped (normal), with a mean of 240 minutes and a standard deviation of 20 minutes.

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Back 61

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Front 62

What percentage of baseball games last less than 270 minutes?

Back 62

93%

Front 63

What percentage of baseball games last more than 260 minutes?

Back 63

16%

Front 64

What percentage of baseball games last between 230 and 280 minutes?

Back 64

33.5%

Front 65

Thirty-three percent of baseball games last less than __________ minutes.

Back 65

231.2

Front 66

Suppose that the amount of time an East Coast commuter spends getting to work each morning averages 40 minutes with a standard deviation of 10 minutes. Assume that the frequency curve for commute times is approximately bell-shaped (normal).

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Back 66

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Front 67

What percentage of commutes are less than 30 minutes?

Back 67

16%

Front 68

What percentage of commutes are more than 20 minutes?

Back 68

97.5%

Front 69

What percentage of commutes are between 23 and 50 minutes?

Back 69

80%

Front 70

Two percent of commutes are more than __________ minutes.

Back 70

60.5

Front 71

A group of college students, all of whom were between the ages of 19 and 24, were surveyed regarding their grade-point averages. The resulting least squares line relating age (x) to grade-point average (y) was: y = 11 – .4x.

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Back 71

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Front 72

Using the line to predict the GPA of a 20-year-old student is

Back 72

valid and will produce a predicted GPA of 3.0

Front 73

Using the line to predict the GPA of a 25-year-old student is

Back 73

invalid due to extrapolation.

Front 74

According to the line, on average, each additional year that students age will

Back 74

decrease their GPA by .4.

Front 75

What is the y-intercept of the least squares line?

Back 75

11

Front 76

The least squares line relating the distance (x, in feet) of a golfer's putt and his success rate (y, in percentage) is: y = 75 – 4x. In the data, the putting distances ranged from 5 to 15 feet.

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Back 76

Blank

Front 77

What is the sample correlation?

Back 77

negative

Front 78

According to the least squares line, on average, each additional foot of distance will

Back 78

decrease the golfer's success rate by 4 percentage points.

Front 79

Using the line to predict the success rate of a golfer putting from a distance of 10 feet is

Back 79

valid and will produce a predicted success rate of 35%.

Front 80

Using the line to predict the success rate of a golfer putting from a distance of 17 feet is

Back 80

invalid due to extrapolation.

Front 81

Which one of the following pairs of variables would likely have a negative correlation?

A. x = age and y = income (for Americans between the ages of 25 and 60)

B. x = average number of hours spent studying each week last semester and y = grade-point average for the semester (for MU students)

C. x = score on the first exam and y = score on the second exam (for students who took Stat 1200 last semester)

D. none of the above (All of the above would likely have positive correlations.)

Back 81

D

Front 82

Suppose that a deterministic relationship exists between two measurement variables, specifically, y = 100 – .85x. What is the correlation between x and y?

Back 82

–1

Front 83

Which one of the following statements about outliers is true?

Back 83

An outlier is a point that is far removed from the rest of the data.

Front 84

Analysis of a particular data set showed a strong, statistically significant correlation between two measurement variables in a sample. Based on this information, which one of the following explanations would a good statistician rule out? (In other words, which one of the following possible explanations would a good statistician believe is not plausible?)

Back 84

There is no relationship in the population, and the relationship in the sample was observed simply by chance

Front 85

Which one of the following pairs of variables would likely have a positive correlation?

A. x = age and y = sale price (for houses sold in Columbia during the past year)

B. x = number of classes skipped last semester and y = grade-point average for the semester (for MU students)

C. x = number of classes skipped during the semester and y = score on final exam (for Stat 1200 students last semester)

D. x = square feet of living space and y = sale price (for houses sold in Columbia during the past year)

Back 85

D

Front 86

Which is true of an outlier in a data set?

A. may have been produced by an error

B. may produce a stronger correlation than would be the case if the outlier were removed

C. may produce a weaker correlation than would be the case if the outlier were removed

D. all of the above

Back 86

D

Front 87

A large manufacturing company reported the following statistics regarding its employee workforce for the past year:

Of a total workforce of 1,000 workers, 200 were laid off.
Of non-white workers, 30% were laid off.
Of white workers, 15% were laid off.
For women, the odds against being laid off were 4 to 1.

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Back 87

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Front 88

Overall, what is the risk of being laid off?

Back 88

.200

Front 89

What is the relative risk of being laid off for non-whites as compared to whites?

Back 89

2.000

Front 90

For non-whites, what are the odds in favor of being laid off?

Back 90

3 to 7

Front 91

What is the proportion of women who were laid off?

Back 91

.200

Front 92

Consider the following information about students at a particular large university for the years 1985 and 2005.

In 2005: 50% of students were female; 60% of students lived within two miles of campus.

In 1985: 40% of students were female; 30% of students lived within two miles of campus.

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Back 92

blank

Front 93

The relative risk of being female in 2005 as compared to 1985 is _____ .

Back 93

1.250

Front 94

The increased risk of living within two miles of campus in 2005 as compared to 1985 is _____ .

Back 94

1.000

Front 95

In 1985, the odds in favor of a student being female were _____ .

Back 95

2 to 3

Front 96

In 2005, the odds against a student living within two miles of campus were _____ .

Back 96

2 to 3

Front 97

A study reported that "1 in 50 women will develop breast cancer by age 50." This information implies that the odds in favor of a woman developing breast cancer by age 50 are

Back 97

1 to 49.

Front 98

In hypothesis testing, the null hypothesis

Back 98

is the "status quo" position.

Front 99

If a hypothesis test were performed at the .05 level of significance, for which of the following p-values would we reject the null hypothesis?

Back 99

.034

Front 100

With regard to contingency tables, what does the saying we "accept the null hypothesis" mean?

Back 100

The relationship between the row and column variables is not statistically significant.

Front 101

A study reports that men have three times the risk of getting a certain disease that women do. What is the increased risk of getting the disease for men as compared to women?

Back 101

2

Front 102

Of fans who attended a college football game this past weekend, 60% are male, 10% are students, 8% are male and are students, 90% rooted for the home team, and 25% are season ticket holders. You may assume rooting for the home team is independent of being male. Suppose that a fan who attended a college football game this past weekend is selected at random.

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Back 102

Blank

Front 103

If a fan who attended a college football game this past weekend is selected at random, what is the probability that the selected fan will be male or a student (or both)?

Back 103

.62

Front 104

If a fan who attended a college football game this past weekend is selected at random, what is the probability that the selected fan will be male and have rooted for the home team?

Back 104

.54

Front 105

If a fan who attended a college football game this past weekend is selected at random, what is the probability that the selected fan will not be a season ticket holder?

Back 105

.75

Front 106

If two fans who attended a college football game this past weekend are independently selected at random, what is the probability that they both will have rooted for the home team?

Back 106

.81

Front 107

A probability assessment that violates one or more of the basic rules of probabilities is said to be

Back 107

incoherent.

Front 108

Suppose that a person named "George" is selected at random. Which one of the following events must have a probability that is at least as large as the rest? (In essence, determine the statement below that is most likely to be true.)

Back 108

George is from Texas.

Front 109

Expected value refers to

Back 109

the average value of a measurement over the long run.

Front 110

A casino offers a "wheel of fortune" game in which a player spins a wheel and, depending on the result, may win different amounts of money. The wheel is divided into three areas—"Win $5" (which is 50% of the area of the wheel), "win $15" (which is 49% of the area of the wheel), and "win $100" (which is 1% of the area of the wheel). If the casino gives you a free spin (does not charge you to play), what is the expected value of your prize?

Back 110

$10.85

Front 111

Of employees in a particular industry, 60% are female. If employees are selected, one at a time, stopping as soon as a male employee is selected, what is the probability that exactly three employees will be selected?

Back 111

.144