Chapter 4: Q 15. (page 227)
Random digits In using Table D repeatedly to choose random samples, you should not always begin at the same place, such as line Why not?
Short Answer
We shouldn't always begin from the same place.
Chapter 4: Q 15. (page 227)
Random digits In using Table D repeatedly to choose random samples, you should not always begin at the same place, such as line Why not?
We shouldn't always begin from the same place.
All the tools & learning materials you need for study success - in one app.
Get started for freeLook, Ma, no hands! Does talking on a hands-free cell phone distract drivers? Researchers recruit student subjects for an experiment to investigate this question. They have a driving simulator equipped with a hands-free phone for use in the study.
(a) Researchers are considering the design shown in the figure below. What type of design is this?
(b) Explain how blocking could be used to improve the design in (a).
(c) Why is it important to randomly assign the treatments within each block?
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.
Doctors and nurses Nurse-practitioners are nurses with advanced qualifications who often act much like primary-care physicians. Are they as effective as doctors at treating patients with chronic conditions? An experiment was conducted with patients who had been diagnosed with asthma, diabetes, or high blood pressure. Within each condition, patients were randomly assigned to either a doctor or a nurse-practitioner. The response variables included measures of the patients’ health and of their satisfaction with their medical care after six months.
(a) Which are the blocks in this experiment: the different diagnoses (asthma, etc.) or the type of care (nurse or doctor)? Why?
(b) Explain why a randomized block design is preferable to a completely randomized design in this setting.
A sampling at the mall You have probably seen the mall interviewer, approaching people passing by with a clipboard in hand. Explain why even a large sample of mall shoppers would not provide a trustworthy estimate of the current unemployment rate.
Customer satisfaction A department store mails a customer satisfaction survey to people who make credit card purchases at the store. This month,
people made credit card purchases. Surveys are mailed to of these people, chosen at random, and people return the survey form. Identify the
population and the sample.
What do you think about this solution?
We value your feedback to improve our textbook solutions.