[R] How do I include a factor in a groupedData object? Meaning and use of inner and outer parameters

[Bert Gunter]

r-sig-mixed-models is likely to be a better list for such queries.

Cheers,
Bert



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 Thu, Mar 22, 2018 at 5:59 AM, Sorkin, John <jsorkin at som.umaryland.edu>
wrote:

> Windows 10 64-bit, R-Studio, R version 3.4.3
>
>
> Several questions relating to groupedData:
>
> (1) I am trying to create a groupedData object that can be used to run an
> analysis that I have been able to urn using lmer. When I include the
> interaction terms in the groupedData opbject I get an error message stating
> that + is not meaningful for factors. How do I include factors in my model?
> See code and error below.
>
> (2) I have read the help file for groupedData multiple times. I am unable
> to understand the meaning or, or the use for the inner= and outer=
> parameters in the call to groupedData. Can someone either explain the
> meaning of these parameters or refer me to a source that give a clear
> explanation?
>
>
> > fit0 <- lmer(THmean~INTRVNTN+factor(TimePtID)+INTRVNTN*factor(
> TimePtID)+(1|PatientID),data=smalldata)
> > sdgd <- groupedData(THmean~INTRVNTN+TimePtID+INTRVNTN*TimePtID|
> PatientID,data=smalldata)
> Warning messages:
> 1: In Ops.factor(INTRVNTN, TimePtID) : ‘+’ not meaningful for factors
> 2: In Ops.factor(INTRVNTN, TimePtID) : ‘*’ not meaningful for factors
>
>
> Thank you,
>
> John
>
>
> John David Sorkin M.D., Ph.D.
> Professor of Medicine
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology and
> Geriatric Medicine
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
>
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