Before revision:  To address these limitations , this article proposes  to estimate the propensity score by fully exploiting its covariate balancing property. We call the resulting estimator the integrated propensity score (IPS) as it is based on integrated moment conditions.
After revision:  To address these limitations , this article proposes to estimate the propensity score by maxizing the covariate distribution balance. The proposed propensity score estimators, which we call the integrated propensity score (IPS) as it is based on integrated moment conditions.