Quiz 9, Module Bias
9. What is the effect of this misclassification on the odds ratio?
Answer —
The Effect:
| Scenario 4 | |||
|---|---|---|---|
|
Breast cancer +
|
Breast cancer -
|
Total
|
|
| Ever used lawn/garden pesticides |
1090
|
1077
|
2167
|
| Never used lawn/garden pesticides |
404
|
459
|
863
|
| Total |
1494
|
1536
|
3030
|
OR = (1,090/404)/(1,077/459) = 1.15
Your effect estimates have been biased towards the null. Why? Look at your cells. Misclassification of exposure was NOT linked to disease status in this scenario, because exposure was misclassified consistently for both D+ and D- participants. Therefore, this is an example of non-differential misclassification, and non-differential misclassification biases estimates towards the null. (Aschengrau & Seage, pp. 278-281)
