Unbiased Estimation of the Average Treatment Effect in Cluster-Randomized Experiments

  title={Unbiased Estimation of the Average Treatment Effect in Cluster-Randomized Experiments},
  author={Joel A. Middleton and P. Aronow},
  journal={Political Methods: Experiments \& Experimental Design eJournal},
Many estimators of the average treatment effect, including the difference-in-means, may be biased when clusters of units are allocated to treatment. This bias remains even when the number of units within each cluster grows asymptotically large. In this paper, we propose simple, unbiased, location-invariant, and covariate-adjusted estimators of the average treatment effect in experiments with random allocation of clusters, along with associated variance estimators. We then analyze a cluster… Expand
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