[R] How do I include a factor in a groupedData object? Meaning and use of inner and outer parameters
lists at dewey.myzen.co.uk
Thu Mar 22 15:30:16 CET 2018
You are only allowed to have the primary covariate on the left hand side
of the vertical bar. Other covariates go in inner or outer.
On 22/03/2018 12:59, Sorkin, John 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 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
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