This paper examines the synthetic control method in contrast to commonly used difference-in-differences (DiD) estimation, in the context of a re-evaluation of a pay-for-performance (P4P) initiative, the Advancing Quality scheme. The synthetic control method aims to estimate treatment effects by constructing a weighted combination of control units, which represents what the treated group would have experienced in the absence of receiving the treatment. While DiD estimation assumes that the effects of unobserved confounders are constant over time, the synthetic control method allows for these effects to change over time, by re-weighting the control group so that it has similar pre-intervention characteristics to the treated group.udududWe extend the synthetic control approach to a setting of evaluation of a health policy where there are multiple treated units. We re-analyse a recent study evaluating the effects of a hospital P4P scheme on risk-adjusted hospital mortality. In contrast to the original DiD analysis, the synthetic control method reports that, for the incentivised conditions, the P4P scheme did not significantly reduce mortality and that there is a statistically significant increase in mortality for non-incentivised conditions. This result was robust to alternative specifications of the synthetic control method
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机译：在重新评估绩效绩效（P4P）计划（先进质量计划）的背景下，本文研究了与通常的差异（DiD）估计相反的综合控制方法。合成控制方法旨在通过构建控制单元的加权组合来估计治疗效果，该控制单元代表治疗组在没有接受治疗的情况下会经历的情况。尽管DiD估算假设未观察到的混杂因素的影响随时间变化是恒定的，但是通过对控制组重新加权，使其具有与治疗组相似的干预前特征，综合控制方法可以使这些影响随时间变化。 ud ud ud我们将综合控制方法扩展到对有多个治疗单位的健康政策进行评估的设置。我们重新分析一项最近的评估医院P4P计划对风险调整医院死亡率的影响的研究。与原始的DiD分析相比，综合控制方法报告说，对于激励条件，P4P方案并没有显着降低死亡率，而在非诱因条件下，死亡率具有统计学上的显着增加。该结果对于综合控制方法的替代规范具有鲁棒性
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