Chapter 1: Q 1.41. (page 16)
Estimating Median Income. Explain why a sample of 30 dentists from Seattle taken to estimate the median income of all Seattle residents is not representative.
The dentists belong to a high-income group whose earnings aren't reflective of the overall population's earnings.
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In Exercises 1.7-1.12, classify each of the studies as either descriptive or inferential. Explain your answers.
Professional Athlete Salaries. From the Statistical Abstract of the United States and the article "Average Salaries in the NBA, NFL, MLB and NHL" by J. Dorish, published on the Yahoo! Contributor Network, we obtained the following data on average professional athletes' salaries for the years 2005 and 2011.
Regarding probability sampling:
(a) What is it?
(b) Does probability sampling always yield a representative sample?
(c) Identify some advantages of probability sampling.
Number of Farms.The National Agricultural Statistics Service (NASS) conducts studies of the number of acres devoted to farms in each county of the United States. Suppose that we divide the United States into the four census regions (Northeast, North Central, South, and West), take a simple random sample of counties from each of the four regions, and combine all four simple random samples into one sample. What type of sampling design have we used? Explain your answer.
Wasp Hierarchical Status. In an issue of Discover (Vol. 26, No. 2, pp. 10-11), J. Netting described the research of E. Tibbetts of the University of Arizona in the article, "The Kind of Face Only a Wasp Could Trust." Tibbetts found that wasps signal their strength and status with the number of black splotches on their yellow faces, with more splotches denoting higher status. Tibbetts decided to see if she could cheat the system. She painted some of the insects ' faces to make their status appear higher or lower than it really was. She then placed the painted wasps with a group of female wasps to see if painting the faces altered their hierarchical status. Was this investigation an observational study or a designed experiment? Justify your answer.
Causes of Death. The National Center for Health Statistics published the following data on the leading causes of death in 2010 in National Vital Statistics Reports. Deaths are classified according to the tenth revision of the International Classification of Diseases.
Rates are per 100,000 population.
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