Question

You are investigating the association between exercise and high blood pressure. You find that the RR of high blood pressure among people who exercise is 0.75. However, people who exercise are also more likely to eat healthy diets, and healthy diets reduce the risk of high blood pressure. Knowing this, what is the most likely adjusted RR you would find if you stratified by whether people ate healthy diets?

0.85

0.4

2

Please show work and calculations.

Answer 1

We know r^2 value lies between 0 and 1 and people who exercise are also more likely to eat healthy diets. So stratification on the basis of people who eat healthy diets will have an r^2 value greater than that of exercise as it will have a stronger effect on blood pressure (since it includes exercise + eating healthy) so as it increases risk of highhigh b pressure would reduce more than that of exercise alone. So we would expect r^2 value to be 0.85 which shows a very high degree of association between the two variables.