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From | Nick Cox <njcoxstata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: -intgph nbreg- drops interaction variables |
Date | Mon, 14 Mar 2011 15:18:13 +0000 |
-tenure- is a measured variable and while that does not rule out modelling with -poisson- it does seem to make application of -nbreg- strange at best and nonsensical at worst. That aside, I read your message as implying that one model is a poor match for the data you throw at it and another a rather better one. That would not seem to imply any problem with either -nbreg- or -intgph-. Is this question a proxy for another one involving your own data? Nick 2011/3/14 Müller Barbara <barbara.mueller@soz.gess.ethz.ch>: > When I use the -intgph- command (from SSC-Archives) with a -nbreg- model, I get the message that my interaction variables were dropped. The analysis can be reproduced with the nlsw88 example Stata-dataset. This is the code I used: > webuse nlsw88 > intgph nbreg tenure, ivars (age south) > > It returns this error message: > ageXsouth has been dropped by nbreg > ageXsouth is the product of the interaction vars > r(499); > > If I use the same command with a -poisson- model, the model runs fine: > intgph poisson tenure, ivars (age south) > > My Stata version and ado-files are up to date. * * 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/