matchit
(Package: MatchIt) :
MatchIt: Matching Software for Causal Inference
matchit is the main command of the package MatchIt, which enables parametric models for causal inference to work better by selecting well-matched subsets of the original treated and control groups. MatchIt implements the suggestions of Ho, Imai, King, and Stuart (2004) for improving parametric statistical models by preprocessing data with nonparametric matching methods. MatchIt implements a wide range of sophisticated matching methods, making it possible to greatly reduce the dependence of causal inferences on hard-to-justify, but commonly made, statistical modeling assumptions. The software also easily fits into existing research practices since, after preprocessing with MatchIt, researchers can use whatever parametric model they would have used without MatchIt, but produce inferences with substantially more robustness and less sensitivity to modeling assumptions. Matched data sets created by MatchIt can be entered easily in Zelig (http://gking.harvard.edu/zelig) for subsequent parametric analyses. Full documentation is available online at http://gking.harvard.edu/matchit, and help for specific commands is available through help.matchit.
The help.matchit command launches html help for Matchit commands and supported methods. The full manual is available online at http://gking.harvard.edu/matchit.
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