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Sensitivity Of The Hazard Ratio To Non-Ignorable Treatment Assignment In An Observational Study, Nandita Mitra, Daniel F. Heitjan

UPenn Biostatistics Working Papers

In non-randomized studies, estimation of treatment effects generally requires adjustment for imbalances in observed covariates. One such method, based on the propensity score, is useful in many applications but may be biased when the assumption of strongly ignorable treatment assignment is violated. Because it is not possible to evaluate this assumption from the data, it is advisable to assess the sensitivity of conclusions to violations of strong ignorability. Lin et al [1] have implemented this idea by investigating how an unmeasured covariate may affect the conclusions of an observational study. We extend their method to assess sensitivity of the treatment …