Quiz 8, Module Bias
8. What is the effect of this misclassification on the odds ratio?
Answer —
The Effect:
| Scenario 3 | |||
|---|---|---|---|
|
Breast cancer +
|
Breast cancer -
|
Total
|
|
|
Ever used lawn/garden pesticides
|
1129
|
739
|
1868
|
|
Never used lawn/garden pesticides
|
365
|
797
|
1162
|
| Total |
1494
|
1536
|
3030
|
OR = (1,129/365)/(739/797) = 3.34
Your effect estimates have been inflated (i.e., biased away from the null). Why? The changes to your numerator offset the changes made in your denominator. Again, this is an example of differential misclassification because your exposure misclassification was based on disease status. In this case, the effect estimate was biased away from the null.
