Effects of Misspecification of the Propensity Score on Estimators of Treatment Effect

A comparison was carried out between the propensity score and prognostic models in estimating treatment effects from observational studies. One issue investigated was the effect of estimating the propensity score on estimators of treatment effect. A second question addressed comparisons of the propensity score and prognostic approach when a confounder is omitted. Third, misspecifications of the propensity score were compared to messpecified response models. In all cases there were two types of models, one involving a continuous and one a binary response.