Thank you so much for the suggestion. I should simplify my formula. Kazz 2012/6/22 Achim Zeileis <achim.zeil...@uibk.ac.at>
> On Fri, 22 Jun 2012, Kazu Nada wrote: > > Thank you so much for the suggestion. >> I want to estimate interactions between "the attributes of the choice set" >> and "subject-specific data (e.g., gender or income)". >> However, y ~ x | z notation is to see the interaction between "the >> alternatives of choice set" and "subject-specific data (e.g., gender or >> income)". >> >> Therefore, I need to put the interaction terms after terms suggesting >> attributes. >> > > Either this is wrong or you did not explain your data properly. (But you > did not follow the posting guide anyway.) > > I suspect that the variables "train", "bus", etc. are 0/1 dummy variables > indicating the alternative and that variables like "inc" are > subject-specific covariates. Then you create alternative-specific > interaction terms which could equivalently and much more conveniently be > created as subject-specific variables. > > Consider the following example with data from the mlogit package: > > ## load package and data > library("mlogit") > data("Fishing", package = "mlogit") > Fish <- mlogit.data(Fishing, varying = c(2:9), > shape = "wide", choice = "mode") > > ## create alternative-specific indicators > Fish$beach <- as.numeric(Fish$alt == "beach") > Fish$boat <- as.numeric(Fish$alt == "boat") > Fish$charter <- as.numeric(Fish$alt == "charter") > Fish$pier <- as.numeric(Fish$alt == "pier") > > ## model with only alternative-specific dummies > ## your style > m1a <- mlogit(mode ~ boat + charter + pier | 0, data = Fish) > ## mlogit style > m1b <- mlogit(mode ~ 0 | 1, data = Fish) > cbind(coef(m1a), coef(m1b)) > > ## model with alternative specific slopes for subject-specific variable > ## your style > m2a <- mlogit(mode ~ boat + charter + pier + I(boat*income) + > I(charter*income) + I(pier*income) | 0, data = Fish) > ## mlogit style > m2b <- mlogit(mode ~ 0 | 1 + income, data = Fish) > cbind(coef(m2a), coef(m2b)) > > So I presume that you could greatly simplify your model formula. It might > be necessary to set up a few of the interactions by hand but I strongly > suspect not all of them! > > hth, > Z > > > Any suggestions would be grateful. >> >> Kaz >> >> 2012/6/8 Achim Zeileis <achim.zeil...@uibk.ac.at> >> On Fri, 8 Jun 2012, Kazu Nada wrote: >> >> Hi, I need help to do "mlogit" including "l( ) >> function. >> When I put following command, >> "Error in parse(text = x) : <text>:2:0:" is shown. >> >> >> (1) Your example is not reproducible for us, see the footer of this >> mail and follow the posting guide. >> >> (2) You manually set up a lot of interaction terms which actually can >> be seen as alternative-specific variables. You can simplify your >> formula considerably if you use mlogit's y ~ x | z notation. See the >> two package vignettes for guidance: vignette(package = "mlogit") >> >> -------- >> res1<-(mlogit(choice~train+**bus+plane+taxi+year+cost >> +I(gen*train)+I(gen*bus)+I(**gen*plane)+I(gen*taxi)+I(gen*** >> year)+I(gen*cost) >> +I(age*train)+I(age*bus)+I(**age*plane)+I(age*taxi)+I(age*** >> year)+I(age*cost) >> +I(prep*train)+I(prep*bus)+I(**prep*plane)+I(prep*taxi)+I(** >> prep*year)+I(prep*c >> ost) >> +I(inc*train)+I(inc*bus)+I(**inc*plane)+I(inc*taxi)+I(inc*** >> year)+I(inc*cost) >> +I(tour*train)+I(tour*bus)+I(**tour*plane)+I(tour*taxi)+I(** >> tour*year)+I(tour*c >> ost) >> +I(ecot*train)+I(ecot*bus)+I(**ecot*plane)+I(ecot*taxi)+I(** >> ecot*year)+I(ecot*c >> ost) >> +I(kibo*train)+I(kibo*bus)+I(**kibo*plane)+I(kibo*taxi)+I(** >> kibo*year)+I(kibo*c >> ost) >> ,data=dat)) >> -------- >> >> I appreciate if you could provide me any suggestion. >> >> Thank you. >> Kaz >> >> [[alternative HTML version deleted]] >> >> ______________________________**________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> >> PLEASE do read the posting guide >> http://www.R-project.org/**posting-guide.html<http://www.R-project.org/posting-guide.html> >> and provide commented, minimal, self-contained, reproducible >> code. >> >> >> >> [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.