Question

A case-control study with 500 cases and 250 controls was conducted to look at the relationship between blood clots and oral contraceptives. Researchers suspect that smoking cigarettes may confound the relationship between blood clots and birth control pills. The crude odds ratio was calculated and equals 3.25. You stratify your 2x2 tables by smoking status and find that the stratum specific odds ratio for smokers is 5.25, and the stratum specific odds ratio for non-smokers is 2.0. Based on these results, we would state the smoking is a(n)

Answer 1

Smoking is acting as a confounding variable in the relationship between blood clots and oral contraceptives.

Step-by-step explanation:

Based on the results of the study, we can conclude that smoking is acting as a confounding variable in the relationship between blood clots and oral contraceptives. The crude odds ratio of 3.25 suggests an increased risk of blood clots associated with the use of birth control pills.

However, when the data is stratified by smoking status, we can see that the stratum-specific odds ratio for smokers is 5.25, indicating a higher risk of blood clots among smokers who use oral contraceptives compared to non-smokers. On the other hand, the stratum-specific odds ratio for non-smokers is 2.0, indicating a lower risk of blood clots among non-smokers who use oral contraceptives.