[R] understanding I() in lmer formula

Bert Gunter bgunter.4567 at gmail.com
Tue Jun 13 21:12:37 CEST 2017

If you don't get a prompt reply here, you might do better posting this
on the r-sig-mixed-models list (for obvious reasons).


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Tue, Jun 13, 2017 at 11:25 AM, Don Cohen <don-r-help at isis.cs3-inc.com> wrote:
>  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.
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