Before revision:  To address these limitations , this article proposes  to estimate the propensity score by fully exploiting its covariate balancing property.
After revision:  To address these limitations , this article proposes a new framework for estimating propensity scores that mimics randomize control trials (RCT) in settings where only observational data is available. More specifically, given that in RCTs the joint distritbution of covariates are balanced between treated and not-treated groups, we propose to estimate the propensity score by fully exploiting its covariate balancing property.