EPI 201 Fall 2017 EPI 201 Lab 3 - Practice Problem Solutions 1. A population-based case-control study will explore the relationship between past oral contraceptive use and postmenopausal endometrial cancer. In sampling the study base from which the cases arose: a. Should women who underwent hysterectomy premenopausally be excluded from the controls? Why or why not? b. Should women who did not use oral contraceptives for religious reasons be excluded from the controls? Why or why not? 2. In a case-control study of stomach cancer among all residents of Connecticut from 2000 to 2002, incident cases are obtained from the state cancer registry. Controls are randomly selected from among residents of Connecticut during the same time period. The investigators wish to assess whether a particular genetic marker (such as blood group A or a particular SNP) increases the risk of stomach cancer. What type of case-control sampling strategy does this describe? What does the odds ratio in this study represent?