Imai, Kosuke. (2005) ``Do Get-Out-The-Vote Calls Reduce Turnout? The Importance of Statistical Methods for Field Experiments.'' American Political Science Review, Vol. 99, No. 2 (May), pp. 283-300.

Telephone canvassing has been one of the most widely used voter mobilization strategies. Yet in their ground-breaking study of a field experiment, Gerber and Green (2000) found that phone calls encouraging people to vote reduce turnout by five percentage points on average. In this article, I introduce statistical methods that enable us to uncover discrepancies between designed experiments and actual implementation. Application of this methodology to Gerber and Green's data shows that their negative finding about get-out-the-vote calls is caused by inadvertent deviations from their stated experimental protocol. I adjust for these implementation errors using a more appropriate statistical method, and demonstrate that telephone canvassing increases voter turnout by about five percentage points on average. This article shows that statistical methods are essential for detecting and correcting complications that commonly arise in field experiments. (Note: This paper was submitted to APSR in August 2002, and was accepted for publication in August 2003. However, its actual publication has been delayed because the original authors have not finished writing their response.)

If you are interested in designing and analyzing (properly) randomized experiments, see Horiuchi, Yusaku, Kosuke Imai, and Naoko Taniguchi (2005). ``Designing and Analyzing Randomized Experiments.''

If you are interested in matching methods, see Ho, Daniel E., Kosuke Imai, Gary King, and Elizabeth A. Stuart (2004). ``Matching as Nonparametric Preprocessing for Reducing Model Dependence in Parametric Causal Inference,'' which comes with easy-to-use software called MatchIt

If you are interested in propensity score methods, see Imai, Kosuke and David A. van Dyk (2004). ``Causal Inference With General Treatment Regimes: Generalizing the Propensity Score,'' Journal of the American Statistical Association, Theory and Methods Vol. 99, No. 467 (September), pp.854-866.