[R] Struggling to compute marginal effects !

[Jim Lemon]

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
<wmulimbi at 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 <drjimlemon at 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
>> <wmulimbi at 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 <drjimlemon at 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
>> >> <wmulimbi at 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 at 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