A researcher is interested in studying the effectiveness of a high-level radiation therapy relative.

A researcher is interested in studying the effectiveness of a
high-level radiation therapy relative to a low-level radiation therapy in
treating stomach cancer. Cancer patients are treated with either of the two
therapies and followed over time to determine if they are cancer-free after
three years. The results of the study are summarized below for patients aged 65
and older and patients aged 64 and younger.

(a) Estimate the common odds ratio using the
Mantel-Haenszel procedure.

(b) Test the null hypothesis that the
common odds ratio is 1. Use a = 0.05.

(c) Compute the estimated odds ratio for
each stratum.

(d) Test the null hypothesis that the odds
ratios found in (c) are equal to 1. Use a = 0.05 for each test.

(e) Comment on the usefulness of the
Mantel-Haenszel procedure for this study.