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From | Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk> |
To | "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu> |
Subject | st: RE: graph interaction in count models |
Date | Thu, 1 Apr 2010 11:31:05 +0100 |
Dear Dali, Another possibility, inspired by the Stata code which can be found here http://homepages.nyu.edu/~mrg217/interaction.html, may be *** webuse nlswork, clear xtset idcode year gen black = race == 2 if inlist(race, 1, 2) xtgee wks_work c.tenure##c.grade south black, /// family(nb) link(log) sum south local south=r(mean) sum black local black=r(mean) sum grade local grade=r(mean) preserve set seed 12345 drawnorm b1-b6, n(10000) means(e(b)) cov(e(V)) clear postutil clear postfile mypost diff_hat diff_lo diff_hi using sim , replace noisily display "start" local a=0 while `a' <= 20 { { generate pred0 =exp( b1*(`a')+b2*(`grade')+b3*`grade'*`a'+b4*`south'+b5*`black'+b6) generate pred1 =exp( b1*(`a')+b2*(`grade'+1)+b3*(`grade'+1)*`a'+b4*`south'+b5*`black'+b6) gen diff=(pred1-pred0) egen diffhat=mean(diff) tempname diff_hat diff_lo diff_hi _pctile diff, p(2.5,97.5) scalar `diff_lo'= r(r1) scalar `diff_hi'= r(r2) scalar `diff_hat'=diffhat post mypost (`diff_hat') (`diff_lo') (`diff_hi') } drop pred0 pred1 diff diffhat local a=`a'+1 display "." _c } display "" postclose mypost use sim, clear gen tenure=0 in 1 qui forval num= 2/20{ replace tenure = tenure[_n-1]+1 in `num' } twoway (line diff_hat tenure, sort lcolor(black) lwidth(thick) ytitle(Effect of a 1pt increase in current grade completed)) (line diff_lo tenure, sort lcolor(black) lwidth(thin) lpattern(dash)) (line diff_hi tenure, sort lcolor(black) lwidth(thin) lpattern(dash)) restore *** Rodolphe -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of D Ma Sent: mercredi 31 mars 2010 20:06 To: statalist@hsphsun2.harvard.edu Subject: st: graph interaction in count models Dear Colleagues, I am trying to graph an interaction between two continuous covariates in a count model (xtgee y x1 x2 x1*x2 ..., family(nb) link(log) vce(robust) nolog). Do you have any suggestions as to how draw such a graph? Thanks! Dali * * 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/