5. Examine the following data from acase-control study, examining the effect ofvitamin E supplementation on stomach cancer. Controls were recruited from the community (neighbors of the cases).

	Cases	Controls
Vitamin E supplementation	33	20
No vitamin E supplementation	67	80

1. Calculate theodds ratio by hand. Show work below, use at least 2 sigfig.
2. Interpret the odds ratio.
3. Use OpenEpi to calculate a 95% CI. (use OpenEpi, 2x2 table option, enter cells of table, click results, copy and paste the 95% confidence interval for the Odds Ratio) 2-points
4. Interpret the 95%CI.
5. Did vitamin E appear toincrease or decrease the odds of being a case? (orneither- meaning no significant association)? __________
6. Was the effect statistically significant? ________
7. Why is it acceptable to use "neighbor controls" for this study?