In Exercises 13–20, determine whether the data are from a discrete or continuous data set.

Statistics Classes In each of her classes, a statistics professor records the number of students who earned a grade of A.

In Exercises 37–44, answer the given questions, which are related to percentages.

Percentages in Advertising In an actual ad for the Club, a device used to discourage car thefts, it was stated that “The Club reduces your odds of car theft by 400%.” What is wrong with this statement?

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Criminology Researchers randomly selected 50 convicted felons from each category of burglary, auto theft, and assault.

In Exercises 13–20, determine whether the data are from a discrete or continuous data set.

Students Your statistics professor records the number of students who pass each of her courses.

In Exercises 37–44, answer the given questions, which are related to percentages.

Workplace Attire In a survey conducted by Opinion Research Corporation, 1000 adults were asked to identify “what is inappropriate in the workplace.” Of the 1000 subjects, 70% said that miniskirts were not appropriate in the workplace.

b. Among the 1000 respondents, 550 said that shorts are unacceptable in the workplace. What percentage of respondents said that shorts are unacceptable in the workplace?

In Exercises 9–12, determine whether the sampling method appears to be sound or is flawed.

Clinical Trials Researchers at Yale University conduct a wide variety of clinical trials by using subjects who volunteer after reading advertisements soliciting paid volunteers.

Parameter and Statistic In a Citrix Security survey of 1001 adults in the United States, it was found that 69% of those surveyed believe that having their personal information stolen is inevitable. Identify the population and sample. Is the value of 69% a statistic or a parameter?

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Cormorant Density Cormorant bird population densities were studied by using the “line transect method” with aircraft observers flying along the shoreline of Lake Huron and collecting sample data at intervals of every 20 km (based on data from Journal of Great Lakes Research).

In Exercises 29–32, indicate whether the observational study used is cross-sectional, retrospective, or prospective.

Marijuana Study Researchers from the National Institutes of Health want to determine the current rates of marijuana consumption among adults living in states that have legalized the use of marijuana. They conduct a survey of 500 adults in those states.

In Exercises 21–24, refer to the sample of body temperatures (degrees Fahrenheit) in the table below. (The body temperatures are from Data Set 5 in Appendix B.)

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Context of the Data Refer to the table of body temperatures. Is there some meaningful way in which each body temperature recorded at 8 AM is matched with the 12 AM temperature?

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Reported and Observed Results A Harris Interactive study involved 1013 adults who were interviewed about washing their hands in restrooms and another 6336 adults who were observed in public restrooms.

E-Cigarette Survey In a survey of 36,000 adults, 3.7% said that they regularly use E-cigarettes (based on data from the National Center for Health Statistics)

b. Is the value of 3.7% a statistic or parameter?

In Exercises 37–44, answer the given questions, which are related to percentages.

Percentages in Advertising An ad for Big Skinny wallets included the statement that one of their wallets “reduces your filled wallet size by 50%–200%.” What is wrong with this statement?

In Exercises 29–32, indicate whether the observational study used is cross-sectional, retrospective, or prospective.

Heart Health Study Samples of subjects with and without heart disease were selected, and then researchers looked back in time to determine whether they took aspirin on a regular basis.

In Exercises 13–20, determine whether the results appear to have statistical significance, and also determine whether the results appear to have practical significance.

Bias in Jury Selection In the case of Casteneda v. Partida, it was found that during a period of 11 years in Hidalgo County, Texas, 870 people were selected for grand jury duty, and 39% of them were Americans of Mexican ancestry. Among the people eligible for grand jury duty, 79.1% were Americans of Mexican ancestry.

Directions in Degrees Standard navigation systems used for aviation and boating are based on directions measured in degrees, with north represented by 0° Relative to north, east is 90°, south is 180°, and west is 270°. What is the level of measurement of such directions measured in degrees?

In Exercises 21–28, determine whether the study is an experiment or an observational study, and then identify a major problem with the study.

Sleep Study When designing the study of a new treatment for insomnia in adults, researchers were criticized because their test subjects consisted of 75 college students. They then expanded the study so that 750 college students were given the treatment.

In Exercises 21–28, determine which of the four levels of measurement (nominal, ordinal, interval, ratio) best describes the given data.

College Students In order to better plan for the incoming freshman class, a college dean asks each newly admitted student to identify their likely major (physics, business, math, psychology, engineering, law, etc.).

In Exercises 13–20, determine whether the data are from a discrete or continuous data set.

Fraud Detection While monitoring Internet traffic in order to detect fraudulent activity, a researcher records the interarrival times (sec) between incoming Internet queries.

In Exercises 29–32, identify the level of measurement of the data as nominal, ordinal, interval, or ratio. Also, explain what is wrong with the given calculation.

Social Security Numbers As part of a project in a statistics class, students report the last four digits of their Social Security numbers, and the average (mean) of those digits is computed to be 4.7.

In Exercises 5–8, determine whether the given source has the potential to create a bias in a statistical study.

AAA The American Automobile Association (AAA) is a not-for-profit federation of motor clubs that provides automotive and travel services. AAA conducts a survey of its members about their use of public transportation versus private automobiles.

In Exercises 21–28, determine whether the study is an experiment or an observational study, and then identify a major problem with the study.

Drinking and Driving A researcher for a consortium of insurance companies plans to test for the effects of drinking on driving ability by randomly selecting 1000 drivers and then randomly assigning them to two groups: One group of 500 will drive in New York City after no alcohol consumption, and the second group will drive in New York City after consuming three shots of Jim Beam bourbon whiskey.

In Exercises 9–12, determine whether the sampling method appears to be sound or is flawed.

Nuclear Power Plants In a survey of 1368 subjects, the following question was posted on the USA Today website: “In your view, are nuclear plants safe?” The survey subjects were Internet users who chose to respond to the question posted on the electronic edition of USA Today.

Discrete/Continuous Data Which of the following describe discrete data?

a. The exact heights of all NBA basketball players

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Highway Strength The New York State Department of Transportation evaluated the quality of the New York State Thruway by testing core samples collected at regular intervals of 1 mile.

In Exercises 29–36, identify what is wrong.

Potatoes In a poll sponsored by the Idaho Potato Commission, 1000 adults were asked to select their favorite vegetables, and the favorite choice was potatoes, which were selected by 26% of the respondents.

In Exercises 37–44, answer the given questions, which are related to percentages.

Marriage Proposals In a survey conducted by TheKnot.com, 1165 engaged or married women were asked about the importance of a bended knee when making a marriage proposal. Among the 1165 respondents, 48% said that the bended knee was essential.

a. What is the exact value that is 48% of 1165 survey respondents?

b. Could the result from part (a) be the actual number of survey subjects who said that a bended knee is essential? Why or why not?

In Exercises 21–24, refer to the sample of body temperatures (degrees Fahrenheit) in the table below. (The body temperatures are from Data Set 5 in Appendix B.)

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Conclusion Given the body temperatures in the table, what issue can be addressed by conducting a statistical analysis of the data?

Quantitative/Categorical Data Identify each of the following as quantitative data or categorical data.

a. The platelet counts in Data Set 1 “Body Data” in Appendix B

In Exercises 25–28, refer to the data in the table below. The entries are for five different years, and they consist of weights (metric tons) of lemons imported from Mexico and U.S. car crash fatality rates per 100,000 population [based on data from “The Trouble with QSAR (or How I Learned to Stop Worrying and Embrace Fallacy)” by Stephen Johnson, Journal of Chemical Information and Modeling, Vol. 48, No. 1].

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Conclusion If we were to use the sample data and conclude that there is a correlation or association between lemon imports and crash fatality rates, does it follow that lemon imports are the cause of fatal crashes?