# [R] How to calculate vif of each term of model in R?

PIKAL Petr petr.pikal at precheza.cz
Fri Apr 17 12:07:34 CEST 2015

```Did you follow my advice/comments?

Cheers
Petr

> -----Original Message-----
> From: Methekar, Pushpa (GE Transportation, Non-GE)
> [mailto:pushpa.methekar at ge.com]
> Sent: Friday, April 17, 2015 11:43 AM
> To: PIKAL Petr
> Subject: RE: How to calculate vif of each term of model in R?
>
> Car package
>
> -----Original Message-----
> From: PIKAL Petr [mailto:petr.pikal at precheza.cz]
> Sent: Friday, April 17, 2015 3:11 PM
> To: Methekar, Pushpa (GE Transportation, Non-GE); r-help at r-project.org
> Subject: RE: How to calculate vif of each term of model in R?
>
> Hi
>
> I did not see any answer so I try.
>
> Your question lacks some info:
>
> Which vif - car or HH?
>
>
> > -----Original Message-----
> > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
> > Methekar, Pushpa (GE Transportation, Non-GE)
> > Sent: Wednesday, April 08, 2015 10:24 AM
> > To: r-help at r-project.org
> > Subject: [R] How to calculate vif of each term of model in R?
> >
> >
> > I am beginner in R doing modelling in R, I loaded excel sheet in R, i
> > have chosen x elements and y elements then fitted model for linear
> and
> > second order regression. Now I have both models. I am bit confused
> how
> > to calculate vif for each term in model like
> >
> > e.g model1<-lm(y1~x1+x2+.....x9) when I am using rms package then
> it's
> > giving me like
> >
> >     vif(model1)
> >
> >        x1         x2         x3         x4         x5         x6
> > x7
> >
> >  6.679692   1.520271   1.667125   3.618439   4.931810   2.073879
> > 13.870630
> >
> >         x8         x9
> >
> >    220.969628 214.034135
> >
> > now i want to compare each term with std vif as vif>=10 and which
> will
> > satisfy this condition i want to delete that term and update model1.
> i
> > have done something like this
> >
> > fun = function(model1) {
> >
> >  for(i in 1:length(model1))    {
> >
> >       v=vif(model1)
> >
> >          ss=any(v[i]>=10)
>
> here you select only one item from vif, Why do you use any?
>
> >
> >                 if(ss==1){update(model1,.~.,-v[i])}
> >
> >                 else{print("no update")}
> >
>
> Why do you change i here?
>
> >                  i<-i+1
> >
> >     }
> >
> >
> >
> >         return(model1)
> >
> >       }
> >
>
> if you want to get rid of all terms bigger than some threshold in once
> you can use
>
> sel <- which(vif(model1)>10)
>
> and select values for update possibly by
>
> update(model1,.~. - names(vif(model1))[sel])
>
> or if you want to get rid one by one you can use
>
> vmax <- which.max(vif(model1))
> and check if max vif value is bigger than 10.
>
> vif(model1)[vmax]>=10
>
> If it is just update with
>
> - names(vif(model1))[vmax])
>
> if it is not do not update.
>
> All of this untested.
>
> Cheers
> Petr
>
> > fun(model1)
> >
> > but giving error as
> >
> > Error in if (ss == 1) { : missing value where TRUE/FALSE needed.
> >
> > please tell me how do i solve this problem.
> >
> >
> >
> >       [[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.
>

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