Chapter 1: Q 2. (page 31)
Almost any inferential study involves aspects of descriptive statistics. Explain why.
To organize any summarised information collected from a sample, descriptive statistics are used in inferential studies.
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Genocide. The document "American Attitudes about Genocide" provided highlights of a nationwide poll with 1000 participants. The survey, conducted by Penn Schoen Berland between June 30 and July 10, 2012, revealed that "66% of respondents believe that genocide is preventable."
(a). Is the statement in quotes an inferential or a descriptive statement? Explain your answer.
(b). Based on the same information, what if the statement had been "66% of Americans believe that genocide is preventable"?
Lobbying Congress. In the special report, "Bitter Pill: Why Medical Bills Are Killing Us" (TIME, Vol. 181, No. 8, 2013), S. Brill presented an in-depth investigation of hospital billing practices that reveals why U.S. health care spending is out of control. One of the many statistics provided in the report is that, during the period from 1998 through 2012, the pharmaceutical and health-care-products industries and organizations representing doctors, hospitals, nursing homes, health services, and HMOs spent \(5.36 billion lobbying Congress.
(a). Under what conditions would the \)5.36 billion lobbying-expenditure figure be a descriptive statistic? Explain your answer.
(b). Under what conditions would the $5.36 billion lobbying- expenditure figure be an inferential statistic? Explain your answer.
The members of a population are numbered 1-90.
(a). Use Table I in Appendix A to obtain SRS of size 5 from the population. Start at the two-digit number in line number 15 and column numbers 25-26, read down the column, up the next, and so on.
(b). If you have access to a random-number generator, use it to solve part (a).
The members of a population are numbered 1-4.
(a). List the 6 possible samples (without replacement) of size 2 from this population.
(b). If an SRS of size 2 is taken from the population, what are the chances of selecting 2 and 3? Explain your answer.
(c). Use Table I in Appendix A to obtain an SRS of size 2 from the population. Start at the single-digit number in line number 17 and column number 7, read down the column, up the next, and so on.
Dental Hygiene: Which Toothbrush? In an experiment reported by J. Singer and D. Andrade in the article " Regression Models for the Analysis of Pretest / Posttest Data " ( Biometrics, Vol . 53, pp . 729-735 ), the effect of using either a conventional or experimental ( hugger ) toothbrush was investigated. Twelve female and 12 male preschoolers were selected. Within each gender group, six were randomly assigned to the conventional toothbrush and the remaining six to the experimental toothbrush. After each subject brushed with the assigned toothbrush, a dental plaque index was measured. The higher the dental plaque index, the greater was the amount of plaque on an individual's teeth.
(a) Is the statistical design described here a completely randomized design or a randomized block design? Explain your answer.
(b) If the statistical design is a randomized block design, what are the blocks?
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