Dear John
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.
Michael
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
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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--
Michael
http://www.dewey.myzen.co.uk/home.html
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