In a clinical trial of

2199

subjects treated with a certain drug,

22

reported headaches. In a control group of

1676

subjects given a placebo,

23

reported headaches. Denoting the proportion of headaches in the treatment group by

pt

and denoting the proportion of headaches in the control (placebo) group by

pc,

the relative risk is

pt/pc.

The relative risk is a measure of the strength of the effect of the drug treatment. Another such measure is the odds ratio, which is the ratio of the odds in favor of a headache for the treatment group to the odds in favor of a headache for the control (placebo) group, found by evaluating

pt/1ptpc/1pc.

The relative risk and odds ratios are commonly used in medicine and epidemiological studies. Find the relative risk and odds ratio for the headache data. What do the results suggest about the risk of a headache from the drug treatment?