Chapter 4: Q 2.1. (page 240)
Outline a completely randomized design for this experiment. Follow the model of
Figure 4.4.
Short Answer
Completely randomized design:
Chapter 4: Q 2.1. (page 240)
Outline a completely randomized design for this experiment. Follow the model of
Figure 4.4.
Completely randomized design:
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Get started for freeEffects of binge drinking A common definition of “binge drinking” is or more drinks at one sitting for men and or more for women. An observational study
finds that students who binge drink have lower average GPA than those who don’t. Identify a lurking variable that may be confounded with the effects of binge drinking. Explain how confounding might occur.
A survey paid for by makers of disposable diapers found that of the sample opposed banning disposable diapers. Here is the actual question:
It is estimated that disposable diapers account for less than of the trash in today’s landfills. In contrast, beverage containers, third-class mail, and yard wastes are estimated to account for about of the trash in landfills. Given this, in your opinion, would it be fair to ban disposable diapers? Explain how the wording of the question could result in bias. Be sure to specify the direction of the bias.
Sleep debt A researcher reported that the average teenager needs 9.3 hours of sleep per night but gets only hours.By the end of a -day school week, a teenager would accumulate about 15 hours of “sleep debt.” Students in a high school statistics class were skeptical, so they gathered data on the amount of sleep debt (in hours) accumulated over time (in days) by a random sample of high school students. The resulting least-squares regression equation for their data is . Do the students have reason to be skeptical of the research study’s reported results? Explain.
Each of the following is a source of error in a sample survey. Label each as sampling error or non sampling error, and explain your answers.
(a) The telephone directory is used as a sampling frame.
(b) The person cannot be contacted in five calls.
(c) Interviewers choose people walking by on the sidewalk to interview.
2. A survey paid for by makers of disposable diapers found that of the sample opposed banning disposable diapers. Here is the actual question:
Does eating dinner with their families improve students’ academic performance? According to an ABC News article, “Teenagers who eat with their families at least five times a week are more likely to get better grades in
school.”19 This finding was based on a sample survey conducted by researchers at Columbia University.
Was this an observational study or an experiment? Justify your answer.
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