Chapter 15, Problem 44CE

Instructions: In all exercises, include software results (e.g., from Excel, MegaStat, or Minitab) to support your calculations. State the hypotheses, show how the degrees of freedom are calculated, find the critical value of chi-square from Appendix E or from Excel’s function =CHISQ.INV.RT(alpha, deg_freedom), calculate the chi-square test statistic, and interpret the p-value. Tell whether the conclusion is sensitive to the level of significance chosen, identify cells that contribute the most to the chi-square test statistic, and check for small expected frequencies. If necessary, you can calculate the p-value by using Excel’s function =CHISQ. DIST.RT(test statistic, deg freedom). Note: Exercises marked * are harder or require optional material.

Refer back to Table 15.11, which shows the distribution of the number of U.S. Supreme Court appointments per year from 1900–1999. During the next 17 years (2000–2016), there were four Supreme Court appointments with one each in the years 2005, 2006, 2009, and 2010. Redo the Poisson GOF test to determine if the assumption of a Poisson distribution is still reasonable for the years 1900–2016. Note that the number of years in this range is 117.