nnmatch estimates the average treatment effect on depvar by comparing outcomes between treated and control observations (as defined by treatvar), using nearest neighbor matching across the variables defined in varlist_nnmatch. nnmatch can estimate either the treatment effect for the treated observations, for the controls, or for the sample as a whole. The program pairs observations to the closest m matches in the opposite treatment group to provide an estimate of the counterfactual treatment outcome. The program allows for matching over a multi-dimensional set of variables (varlist_nnmatch), giving options for the weighting matrix to be used in determining the optimal matches. It also allows exact matching (or as close as possible) on a subset of variables. In addition, the program allows for bias correction of the treatment effect, and estimation of either the sample or population variance, with or without assuming a constant treatment effect (homoskedasticity). Finally it allows observations to be used as a match more than once, thus making the order of matching irrelevant.
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Publisher Info
Software component provided by Boston College Department of Economics in its series Statistical Software Components with number
S439701.
Size: Programming language: Stata Requires: Stata version 8.0 Date of creation: 10 Jun 2004 Date of revision: Handle: RePEc:boc:bocode:s439701
Note: This module may be installed from within Stata by typing "ssc install nnmatch". Windows users should not attempt to download these files with a web browser. Contact details of provider: Postal: Boston College, 140 Commonwealth Avenue, Chestnut Hill MA 02467 USA Phone: 617-552-3670 Fax: +1-617-552-2308 Email: Web page: http://fmwww.bc.edu/EC/ More information through EDIRC
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