Why Propensity Scores Should Not Be Used for Matching

@article{King2019WhyPS,
  title={Why Propensity Scores Should Not Be Used for Matching},
  author={Gary King and Richard A. Nielsen},
  journal={Political Analysis},
  year={2019},
  volume={27},
  pages={435 - 454}
}
We show that propensity score matching (PSM), an enormously popular method of preprocessing data for causal inference, often accomplishes the opposite of its intended goal—thus increasing imbalance, inefficiency, model dependence, and bias. The weakness of PSM comes from its attempts to approximate a completely randomized experiment, rather than, as with other matching methods, a more efficient fully blocked randomized experiment. PSM is thus uniquely blind to the often large portion of… 

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