Chapter 1: Problem 33
Describe the sample and describe a reasonable population. Five hundred Canadian adults are asked if they are proficient on a musical instrument.
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State whether or not the sampling method described produces a random sample from the given population. The population is all people who visit the website \(C N N\).com. All visitors to the website are invited to take part in the daily online poll.
How Many People Wash Their Hands After Using the Washroom? In Example 1.10 on page \(16,\) we introduce a study by researchers from Harris Interactive who were interested in determining what percent of people wash their hands after using the washroom. They collected data by standing in public restrooms and pretending to comb their hair or put on make-up as they observed patrons' behavior. \({ }^{27}\) Public restrooms were observed at Turner's Field in Atlanta, Penn Station and Grand Central Station in New York, the Museum of Science and Industry and the Shedd Aquarium in Chicago, and the Ferry Terminal Farmers Market in San Francisco. Of the over 6000 people whose behavior was observed, \(85 \%\) washed their hands. Women were more likely to wash their hands: \(93 \%\) of women washed, while only \(77 \%\) of men did. The Museum of Science and Industry in Chicago had the highest hand-washing rate, while men at Turner's Field in Atlanta had the lowest. (a) What are the cases? What are the variables? Classify each variable as quantitative or categorical. (b) In a separate telephone survey of more than 1000 adults, more than \(96 \%\) said they always wash their hands after using a public restroom. Why do you think there is such a discrepancy in the percent from the telephone survey compared to the percent observed?
A relationship between two variables is described. In each case, we can think of one variable as helping to explain the other. Identify the explanatory variable and the response variable. Blood alcohol content (BAC) and number of alcoholic drinks consumed
In Exercises 1.40 to \(1.45,\) state whether or not the sampling method described produces a random sample from the given population. The population is incoming students at a particular university. The name of each incoming student is thrown into a hat, the names are mixed, and 20 names (each corresponding to a different student) are drawn from the hat.
Armoring Military Planes During the Second World War, the U.S. military collected data on bullet holes found in B-24 bombers that returned from flight missions. The data showed that most bullet holes were found in the wings and tail of the aircraft. Therefore, the military reasoned that more armor should be added to these regions, as they are more likely to be shot. Abraham Wold, a famous statistician of the era, is reported to have argued against this reasoning. In fact, he argued that based on these data more armor should be added to the center of the plane, and NOT the wings and tail. What was Wald's argument?
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