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n a clinical trial of 2120 subjects treated with a certain? drug, 29 reported he

ID: 3126864 • Letter: N

Question

n a clinical trial of

2120

subjects treated with a certain? drug,

29

reported headaches. In a control group of

1611

subjects given a? placebo,

27

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/(1Pt) over Pc/(1-Pc)

.

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?

Explanation / Answer

The following is the given informaiton :

Relative risk = (29/2110)/(27/1611) = 0.82

Odds ratio = (29/2081)/(27/1584) = 0.8176

The RR value is less than one, there is decreased risk for headache for treatment group

Present head ache Not present head ache Total Treatment Group 29 2081 2110 Control Group 27 1584 1611