[R-sig-ME] [R] understanding I() in lmer formula

[Dan Brooks]

Related to your second question about ||, I believe || is shorthand for
uncorrelating the slope and intercept, e.g:
fm3 <- lmer(Reaction~Days+(Days+0|Subject)+(1|Subject),data=sleepstudy)
fm4 <- lmer(Reaction~Days+(1+Days||Subject),data=sleepstudy)

As opposed to:
fm2 <- lmer(Reaction~Days+(Days+1|Subject),data=sleepstudy)
or simply:
fm1 <- lmer(Reaction~Days+(Days|Subject),data=sleepstudy)

Although happy to be corrected by Ben Bolker if there's more complex
examples where this isn't quite right.

Best-
Dan

On Tue, Jun 13, 2017 at 4:42 PM, Andrew Robinson <mensurationist at gmail.com>
wrote:

> Don,
>
> can you provide a minimal executable example?
>
> Cheers,
>
> Andrew
>
> On 14 Jun 2017, 6:15 AM +1000, peter dalgaard <pdalgd at gmail.com>, wrote:
> > Not that I really have a clue, but what is that "~" doing in the error
> message??
> >
> > -pd
> >
> > > On 13 Jun 2017, at 21:20 , Don Cohen <don-r-help at isis.cs3-inc.com>
> wrote:
> > >
> > > Bert Gunter suggested posting this here:
> > >
> > > Is there a difference between I(x*y) and I(y*x) ?
> > > I have a call to lmer that results in this complaint:
> > > Error in is.alpha2.subordinate * ~z.min.co.res :
> > > non-numeric argument to binary operator
> > > when I change this line:
> > > I(is.alpha2.subordinate*z.min.co.res)+
> > > to this:
> > > I(z.min.co.res*is.alpha2.subordinate)+
> > > the complaint goes away.
> > > I'd like to understand why.
> > >
> > > _______________________________________________
> > > R-sig-mixed-models at r-project.org mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >
> > --
> > Peter Dalgaard, Professor,
> > Center for Statistics, Copenhagen Business School
> > Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> > Phone: (+45)38153501
> > Office: A 4.23
> > Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
> >
> > _______________________________________________
> > R-sig-mixed-models at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >
>
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