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From |
"Austin Nichols" <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: displaying/summarizing covariate balance |

Date |
Fri, 19 Sep 2008 12:26:30 -0400 |

Pierre-- I should have also mentioned that you can also use these models to reweight the data so that the means of all x* variables are the same across the two groups (note that matching is also a form of reweighting), as alluded to in SJ7(4): http://www.stata-journal.com/article.html?article=st0136 For example: use http://fmwww.bc.edu/ec-p/data/wooldridge/card, clear loc x "age exper* black smsa66 reg662-reg669" g m=marr==1 qui hotelling `x', by(m) loc F=(r(N)-r(k)-1)/(r(N)-2)/r(k)*r(T2) loc p=Ftail(r(k),r(df),`F') di "F=" `F' ", p=" `p' qui reg m `x' di "F=" e(F) ", p=" Ftail(e(df_m),e(df_r),e(F)) qui logit m `x' predict p g rwt=cond(m,1-p,p) qui reg m `x' [aw=rwt] di "F=" e(F) ", p=" Ftail(e(df_m),e(df_r),e(F)) *to put the -hotelling- output into a table, I suggest -estout- from SSC: est clear qui reg id `x' if m==0 est sto C estadd summ: * tempfile C est save `C' est clear qui reg id `x' if m==1 est sto T estadd summ: * estadd scalar Ftest `F' est use `C' est sto C esttab C T, main(mean) aux(sd) scalar(Ftest) nodep nostar nocons With the -rtf- option on -esttab- you can write to a file with the .doc extension and double-click to open in MS Word, and with the -tex- option you can write a LaTeX table. On Fri, Sep 19, 2008 at 10:42 AM, Austin Nichols <austinnichols@gmail.com> wrote: > Pierre Azoulay <pierre.azoulay@gmail.com>: > You are using -nnmatch- from SSC, I take it? Just use the same tests > as used for testing balance of (pretreatment) covariates under random > assignment: if treatment is a var tr taking on values 0/1 and > covariates are x* then > hotelling x*, by(tr) > and > reg tr x* > give the same F-test for differences in means (add ,robust to the > latter to relax assumptions about equal variance, or use logit or > probit for alternative discriminants). Or did you want to compare the > whole distribution of values for all x* (in which case a bunch of > kernel density graphs are in order)? > > On Fri, Sep 19, 2008 at 10:18 AM, Pierre Azoulay > <pierre.azoulay@gmail.com> wrote: >> Dear Statalisters, >> >> I am doing a very simple nearest-neighbor matching exercise for a >> paper of mine, and I would be interested in suggestiopns on how best >> to summarize and/or display covariate balance among the matched units, >> if possible with code examples. A search on "covariate balance" in >> stata list did not reveal anything enlightening. > * * 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/

**References**:**st: displaying/summarizing covariate balance***From:*"Pierre Azoulay" <pierre.azoulay@gmail.com>

**Re: st: displaying/summarizing covariate balance***From:*"Austin Nichols" <austinnichols@gmail.com>

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