Homework #12: Not due - for practice only

Conceptual problems: Chapter 18: 1, 3, 4a, 7ac, 8acd

Computational problems:
Chapter 18: 14. Please answer the following:

  • Calculate the standard error and a confidence interval for the proportion who responded when asked for 17 cents.
  • Use the proportions to reconstruct the contingency table for these data. Round the counts to integers.
  • Test whether the proportion of targets responding is the same in two treatments (ask for 17 cents or ask for 25 cents).
  • Calculate the log odds ratio and its standard error.
  • Calculate a 95% confidence interval for the odds ratio.

    Chapter 19: 5 (or 11). Using the Crab parasite data, test whether parasites are equally likely to be found on the two species of crabs. N.B. use a 2-sided p-value, not the 1-sided p-value requested in problem 11.

    Chapter 19:9. Ignore the book's questions. Construct the contingency table for the two departments combined. I.e. imagine you were given the data without being told which department department a student belonged to. Do you see that Eagle has the higher percentage of passes in the combined data? Can you explain why the combined data gives a different impression than do the two department-specific tables?

    Useful SAS stuff:

  • vitc.sas Contingency table analysis, including Chi-square, Fisher exact test and estimation of odds ratios.