Thank you both for your help. I've tried VGAM and it seems useful. Cheers David
On 27/02/06, Robert Duval <[EMAIL PROTECTED]> wrote: > I don't know if I understand your problem very well but the first > reference that comes to mind is > > James Heckman, "Dummy Endogenous Variables in a Simultaneous Equation > System," Econometrica, (July 1978). > > also you might find a good survey of the literature on > > Francis Vella "Estimating models with sample selection bias: A > survey," Journal of Human Resources, 1998, Vol 33 pp 127-169. > > I don't know how many of the methods here proposed are already > implemented in R, but in principle many of them are Likelihood models > that you could program. > > > best > robert > > > On 2/27/06, David Hugh-Jones <[EMAIL PROTECTED]> wrote: > > Hi > > > > I have data for voting behaviour on two (related) binary votes. I want > > to examine the second vote, running separate regressions for groups > > who voted different ways on the first vote. As the votes are not > > independent, I guess that there is an issue with selection bias. > > > > So, I think I would like to fit a heckit style model but with a binary > > dependent variable - so, in effect, two successive probits. Is there a > > way to do it in R? (Alternatively: am I thinking about this the right > > way?) > > > > Cheers > > David > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html