[R] Mixed model

From: Stephen <szlevine_at_nana.co.il>
Date: Mon 20 Jun 2005 - 18:29:11 EST

Dear Fellow R users,  

I am fairly new to R and 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.  

Based on this

Dataset <- read.table("C:/Program Files/R/rw2010/data/miss/model1.dat", header=TRUE, sep="\t", na.strings="NA", dec=".", strip.white=TRUE)

require (nlme)

model.mix <- lme (trans1 ~ Index1 + grp,

                  random = ~ constant | id / grp ,

                  data = Dataset,

                  na.action = "na.exclude")


# where trans1 is the factor of the repeated measures of the scale.

# Index is the trial number, grp the group, and id the subject number.  

I would like to split the results, just like SPSS splitfile by a variable in the Dataset called runnb

I have tried using:  

      by (Dataset, runnb,

            function (x) (lme (trans1 ~ Index1 + grp,

            random = ~ constant | id / grp ,

            data = Dataset,

            na.action = "na.exclude") )


but to no avail . as my computer hangs and I set my GUI to --mdi --max-mem-size=1200M.  

Any ideas as to how to splitfile the results SPSS style would be most appreciated?  

Also, does lme do pairwise deletion?  

By the way

> version

platform i386-pc-mingw32

arch i386

os mingw32

system i386, mingw32


major 2

minor 1.0

year 2005

month 04

day 18

language R

Windows XP Pro.  

Many thanks


Ps as its my first time on this group - neat program!

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