A cohort study was conducted to examine cigarette smoking and the risk of oral cancer. The investigators selected exposed and unexposed subjects so that they had the exactly same distribution of race. This method to address confounding by race is called:
a. Restriction
b. Stratification
c. Matching

c. Matching

Explanation:

This method used to address confounding by race is matching. In this study the exposed and unexposed group are match on a confounder which is race. Matching is a statistical method that involves finding units that are similar and closest in terms of observable characteristics and matching them together, it involves comparing the treated and untreated units based on similar characteristics.

economic

carefully examine the map above. based on your knowledge of colonialism in africa, the area attributed to belgium on this map is most likely the democratic republic of the congo.