In that case, I can't work out why the first model fails but not the second. I would start looking at "Data" to see what it contains. if:
object2 <- polr(Inc ~ Training ,Data,Hess = T,method = "logistic" ) works, the problem may be with the "Adopt" variable. Jim On Tue, Mar 20, 2018 at 10:55 AM, Willy Byamungu <wmuli...@email.uark.edu> wrote: > Sorry, do not read "Inc_reliable_fromNTA" I did a mistake in the email I > sent you. It should be just "Inc". > > The situation looks like this > > Data$Inc <- ordered(Data$Inc = > c("Not_reliable_at_all","Less_reliable","Somehow_reliable","Very reliable")) > > First model > object1 <- polr(Inc ~ Adopt ,Data,Hess = T,method = "logistic") > > Marginal effect for object1: > ocME(object1) > Error in eval(predvars, data, env) : > numeric 'envir' arg not of length one > > Second model > object2 <- polr(Inc ~ Adopt + Training ,Data,Hess = T,method = "logistic" ) > > Marginal effect for object2: > ocME(object2) > effect.Not_reliable_at_all effect.Less_reliable effect.Somehow_reliable > effect.Very reliable > Adopt -0.073 -0.057 > -0.064 0.193 > Training -0.283 -0.135 > -0.051 0.469 > > > On Mon, Mar 19, 2018 at 6:46 PM, Jim Lemon <drjimle...@gmail.com> wrote: >> >> Hi Willy, >> I had a look at the "erer" manual, and it looks like a (somewhat) >> misleading error message. I don't know where "Inc_reliable_fromNTA" >> may be, but it looks like the ocME function can't find it, which leads >> to the "environment" error message. You have defined "Inc" as an >> element of "Data" and when that is used in the model, the ocME >> function works. I suspect that "Inc_reliable_fromNTA" is not an >> element of "Data" and this is why ocME cannot find it. >> >> Jim >> >> >> On Tue, Mar 20, 2018 at 10:26 AM, Willy Byamungu >> <wmuli...@email.uark.edu> wrote: >> > Dear Jim, >> > >> > Thank you very much for your help. >> > >> > My R-coding looks like this: >> > >> > Data$Inc <- ordered(Data$Inc = >> > c("Not_reliable_at_all","Less_reliable","Somehow_reliable","Very >> > reliable")) >> > >> > First model >> > object1 <- polr(Inc_reliable_fromNTA ~ Adopt ,Data,Hess = T,method = >> > "logistic") >> > >> > Marginal effect for object1: >> > ocME(object1) >> > Error in eval(predvars, data, env) : >> > numeric 'envir' arg not of length one >> > >> > Second model >> > object2 <- polr(Inc ~ Adopt + Training ,Data,Hess = T,method = >> > "logistic" ) >> > >> > Marginal effect for object2: >> > ocME(object2) >> > effect.Not_reliable_at_all effect.Less_reliable effect.Somehow_reliable >> > effect.Very reliable >> > Adopt -0.073 -0.057 >> > -0.064 0.193 >> > Training -0.283 -0.135 >> > -0.051 0.469 >> >> >> > >> > The model computing requires package "MASS" and marginal effects require >> > "ERER". As you can see above, in the first case it succeed to provide >> > results but in the first case NO. >> > >> > What do you think? By the way, what do you mean by inappropriate >> > environment >> > and predvars? >> > >> > Looking forward to hearing from you. >> > >> > Regards, >> > >> > Willy >> > >> > On Mon, Mar 19, 2018 at 5:33 PM, Jim Lemon <drjimle...@gmail.com> wrote: >> >> >> >> Hi Willy, >> >> The error message may be due to passing an inappropriate environment. >> >> I don't have the "erer" package, but if that function has a default >> >> for the environment argument, perhaps passing just the "predvars" and >> >> "data" arguments will work. >> >> >> >> Jim >> >> >> >> On Tue, Mar 20, 2018 at 8:24 AM, Willy Byamungu >> >> <wmuli...@email.uark.edu> >> >> wrote: >> >> > Dear Oscar, >> >> > and any other R-project person, >> >> > >> >> > Can you please help me to figure out the meaning of the following >> >> > error >> >> > message in red ? >> >> > >> >> > Error in eval(predvars, data, env) : >> >> > numeric 'envir' arg not of length one >> >> > >> >> > I computed ordered logit models using 'polr' in R (I just followed >> >> > the >> >> > guidance a handout I found on princeton.edu about logit, probit and >> >> > multinomial logit models) . The summary results are obtained without >> >> > any >> >> > problem. *However*, when I'm using the package 'erer' to compute the >> >> > marginal effects for the ordered logit models, I'm just getting the >> >> > error >> >> > message above. >> >> > >> >> > Please HELP !!!! >> >> > >> >> > Willy >> >> > >> >> > >> >> > -- >> >> > Willy Mulimbi B. >> >> > AEAB Grad Student & Fulbright Scholar >> >> > Tel. (+1) 479-316-5981 >> >> > Fayetteville, AR >> >> > >> >> > [[alternative HTML version deleted]] >> >> > >> >> > ______________________________________________ >> >> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> >> > 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. >> > >> > >> > >> > >> > -- >> > Willy Mulimbi B. >> > AEAB Grad Student & Fulbright Scholar >> > Tel. (+1) 479-316-5981 >> > Fayetteville, AR > > > > > -- > Willy Mulimbi B. > AEAB Grad Student & Fulbright Scholar > Tel. (+1) 479-316-5981 > Fayetteville, AR ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.