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From | TA Stat <tastat@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Manually compute IPTW for PS matching? |
Date | Sat, 17 Mar 2012 00:33:39 +0700 |
Thanks for your reply. Actually, I did compute iptw manually already. I am not sure whether I do need iptw with 1:1 matching, but not 1:n matching. I am comparing 3 levels variable, (treatment A vs C and B vs C) on survival events by Cox PH model. I am not quite sure about the weight that Stata produce with 1:1 matching. That is the reason why I get confused. Thanks Pete On Fri, Mar 16, 2012 at 9:51 PM, Adam Olszewski <adam.olszewski@gmail.com> wrote: > Hi Pete, > Are you doing PS matching or weighting? If you're only doing 1:1 > matching then IPTW is not necessary. > I usually calculate IPTW manually: > > gen iptw = treatment/pscore + (1-treatment)/(1-pscore) > > I am not aware of any "step-by-step" Stata-specific tutorial on PS > matching. It is a complex process if to be done properly, with > appropriate diagnostics and many potential pitfalls. One brief general > intro is at: > > http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144483/ > > Also, read the help for -pscore2- -pstest- -psgraph- and -pbalchk- thoroughly. > > Adam Olszewski > > On Fri, Mar 16, 2012 at 2:03 AM, TA Stat <tastat@gmail.com> wrote: >> Dear All >> >> This is a simple question. After run psmatch2 command (1:1 matching), >> I got pscore, treated, support, weight, n1, nn, pdif variables. Do I >> have to manually calculate IPTW? Is any recommended step-by-step >> illustration of PS matching in Stata available? >> >> Thanks >> Pete >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/statalist/faq >> * http://www.ats.ucla.edu/stat/stata/ > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/