Medicine and Health Sciences Commons^™

Should Adjustment For Covariates Be Used In Prevalence Estimations, Wenjun Li, Edward J. Stanek, Elizabeth R. Bertone-Johnson

Elizabeth R. Bertone-Johnson

BACKGROUND: Adjustment for covariates (also called auxiliary variables in survey sampling literature) is commonly applied in health surveys to reduce the variances of the prevalence estimators. In theory, adjusted prevalence estimators are more accurate when variance components are known. In practice, variance components needed to achieve the adjustment are unknown and their sample estimators are used instead. The uncertainty introduced by estimating variance components may overshadow the reduction in the variance of the prevalence estimators due to adjustment. We present empirical guidelines indicating when adjusted prevalence estimators should be considered, using gender adjusted and unadjusted smoking prevalence as an illustration. …