 
 

Hi All,

 

I am currently conducting a mixed model. I have 7 repeated measures on a
simulated clinical trial. If I understand the model correctly, the
outcome is the measure (as a factor) the predictors are clinical group
and trial (1-7). The fixed factors are the measure and group. The random
factors are the intercept and id and group.

 

I tried using 2 functions to calculate mixed effects.

Following previous correspondence .

 

Dataset <- read.table("C:/Program Files/R/rw2011/data/miss/model1a.dat",
header=TRUE, sep="\t", na.strings="NA", dec=".", strip.white=TRUE)

attach(Dataset)

 

require (nlme)

with(Dataset, table(runnb, id, grp)) 

b.lvls <- table(Dataset$runnb) 

nb <- length(b.lvls) 

fit <- vector(mode="list", nb) 

 

for(i in 1:nb) 

 fit[[i]]<- lme (trans1 ~ Index1 + grp, 

            random = ~ 1 | id / grp ,

            data = Dataset,

            na.action = "na.exclude")

 

 

This (above) worked OK only I am having memory problems.

I have a gig of RAM set at --sdi --max-mem-size=512M (complete version
below)

I am wondering if running the file as a database be slower / faster?

 

Then I read that lme4 does it quicker and more accurately 

so I thought that I should re-run the code but from the for line:

 

> for (i in 1:nb)

+  fit[[i]]  <- lmer(trans1 ~ Index1 + grp + (1|id:grp) + (1|id), 

+ Dataset, na.action = na.exclude)

 

Producing

 

Error in lmer(trans1 ~ Index1 + grp + (1 | id:grp) + (1 | id), Dataset,
: 

        flist[[2]] must be a factor of length 200000

In addition: Warning messages:

1: numerical expression has 200000 elements: only the first used in:
id:grp 

2: numerical expression has 200000 elements: only the first used in:
id:grp

 

Any advice on the source and handling of this error would be
appreciated?

 

version:         _              

platform i386-pc-mingw32

arch     i386           

os       mingw32        

system   i386, mingw32  

status                  

major    2              

minor    1.1            

year     2005           

month    06             

day      20             

language R      

Windows XP Pro.

Many thanks

Stephen


???? ?"? ???? ????
http://mail.nana.co.il

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