Synthetic controls with multiple outcomes
将合成控制法推广到多结果变量框架，利用相关结果变量补充预处理时间维度，降低过拟合风险，提高估计可靠性，尤其适用于预处理期较短的情况。
Summary We generalize the synthetic control (SC) method to a multiple-outcomes framework in which the conventional pretreatment time dimension is supplemented with the extra dimension of related outcomes in computing the SC weights. This generalization reduces the risk of overfitting and improves the reliability of the SC method, particularly when the number of pretreatment periods is small. To illustrate our method, we provide a new perspective on the classic SC application to German reunification in 1990.