[R-sig-ME] Please post to the listserv

[Prathiba Natesan Batley]

Hello:
Could you please post the following to the listserv?

I am in a bit of a pickle here. I tried running a fixed effects model with
autocorrelation on a very small dataset (single case design). My syntax
look like this:
  lm2 <- lme(y ~ 1 + treatment, random = ~1|pid, data = df, correlation =
corAR1())
I want to obtain the phi coefficient which I see is in
lm2$modelStruct$corStruct. But the moment I extract it and put it into a
matrix it stores a different value. In this case it should be -0.17 but is
stored as -0.35. Pls see below:
> lm.2$modelStruct$corStruct
Correlation structure of class corAR1 representing
       Phi
-0.1743846

> cbind(1, lm.2$modelStruct$corStruct)
     [,1]       [,2]
[1,]    1 -0.3523706

Here is a sample dataset and syntax
            d=.5
            ICC=.1
            m=6
            phi=0
            n=5
            rep=1
            df <- read.csv(paste0("data", d, "-", ICC, "-", phi, "-", m,
"-", n, "_", rep, ".csv"))
lm2 <- lme(y ~ 1 + treatment, random = ~1|pid, data = df, correlation =
corAR1())
phi.hps <- c(lm2[[1]][2]) #or lm2$modelStruct#corStruct