Instructions:Complete the homework questions listed below. Where indicated, show your work.

A retrospective cohort study is conducted to estimate the relationship between alcohol consumption (exposure) and 20-year risk of ischemic stroke. Average monthly alcohol consumption was measured over a period of 6 months by use of a reliable and valid self-report questionnaire. However, the investigators are concerned that there may have been some misclassification with respect to exposure status.

The actual data obtained from the study are as follows:

Monthly alcohol consumption

Outcome (ischemic stroke)

Monthly alcohol consumption Outcome (ischemic stroke)

Total

No Yes

None/low 1550 38 1588

Moderate 1944 34 1978

High 1080 41 1121

Total 4574 113 4687

1.From the above, calculate the incidence of ischemic stroke for each level of alcohol consumption. Because the overall risk is low, calculate your answers to 4 decimal places. Show your work.

a)None/low:38 / 1588 = 0.0239 (are these right?)

b)Moderate:34 / 1978 = 0.0171

c)High:41 / 1121 = 0.0365