http://www.youtube.com/subscription_center?add_user=wildsc0p
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codes are available from http://www.ehsankarim.com/software/matching.R - open it using any text editor (codes for nearest neighborhood 1:1, neighborhood 1:4, caliper, subclass, full matching included that allows selecting ~ matched samples of the treated and control groups with similar propensity scores) . See the documentation of MatchIt package in http://cran.r-project.org/web/packages/MatchIt/index.html and http://imai.princeton.edu/research/files/matchit.pdf for more details.
