I propose a methodology for constructing counterfactuals with respect to changes in policy rules that does not require fully specifying a particular model yet is not subject to Lucas critique. It applies to a class of dynamic stochastic models whose equilibria are well approximated by a linear representation. It rests on the insight that many such models satisfy a principle of counterfactual equivalence: they are observationally equivalent under a benchmark policy and yield an identical counterfactual equilibrium under an alternative one.

中文翻译：

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政策反事实的半结构方法论

我提出了一种针对政策规则变化构建反事实的方法，该方法不需要完全指定特定模型，但不受卢卡斯批评的约束。它适用于一类动态随机模型，其均衡可以通过线性表示很好地近似。它基于这样的见解，即许多此类模型满足反事实等价原则：它们在基准政策下在观察上是等价的，并且在替代政策下产生相同的反事实均衡。