Chapter 15, Problem 39CE

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.

The table below shows the number of ATM customer arrivals per minute in 60 randomly chosen minutes. Research question: At α = .025, can you reject the hypothesis that the number of arrivals per minute follows a Poisson process?