Before revision:  We show that the average of separate SCM fits does not necessarily achieve good balance for the average of the treated units , leading to possible bias in the estimated effect. We propose "partially pooled" SCM weights that instead minimize both average and state-specific imbalance, and show that the resulting estimator controls biasunder a linear factor model.
After revision:  We show that the average of separate SCM fits does not necessarily achieve good balance for the average of the treated units . We then propose "partially pooled" SCM weights that instead minimize both average and state-specific imbalance, and show that the resulting estimator controls biasunder a linear factor model.