The observed agreement was calculated to test the strength of agreement instead of the Kappa statistic because the latter is influenced substantially by trait prevalence and imbalanced marginal distributions [ 14- 18].
Finally, we carried out a post hoc sensitivity analysis, restricting the study population to patients without diabetes because of an imbalance in prevalence of diabetes between treatment groups.
Many of these diseases show a marked gender imbalance in prevalence, and cross-talk between estrogen and BMP signaling has been noted in systems throughout the body [ 11- 13].
This lack of adjustment somewhat limits this example, since even a small association with outcome of a covariate with such an imbalance in prevalence between the treatment groups may contribute substantively to overall confounding.
For symmetrically imbalanced cases, we notice that when the prevalence index (PI) is large, kappa has a low value [scenarios 2 and 3].
Confounding bias of the RR occurs when the prevalence of a risk factor (or set of risk factors) for breast cancer death is imbalanced across the compared groups.
But the relationship is imbalanced.
Yet the game is even more imbalanced.
