Please i need help. A cohort study was undertaken to examine the association between high lipid level and

coronary heart disease (CHD). Participants were classified as having either a high lipid level

(exposed) or a low or normal lipid level (unexposed). Because age is associated with both

lipid level and risk of heart disease, age was considered a potential confounder or effect

modifier and the age of each subject was recorded. The following data describes the study

participants: Overall, there were 11,000 young participants and 9,000 old participants. Of the

4,000 young participants with high lipid levels, 20 of them developed CHD. Of the 6,000 old

participants with high lipid levels, 200 of them developed CHD. In the unexposed, 18 young

and 65 old participants developed CHD.

Construct the appropriate two by two tables using the data given above.

Calculate the appropriate crude ratio measure of association combining the data for

young and old individuals.

Perform a stratified analysis and calculate the appropriate stratum-specific ratio

measures of association.

Do the data provide evidence of effect measure modification on the ratio scale?