I'm trying to investigate my data with linear mixed model and are seeking advise how to write the model in R. I was trying to get hold of the recommended book from Bates et al, but neither the major bookshop nor our university library had the book. My data is mirroring the example given in the appendix of John Foxes book "Applied Regression" with a small exception.
I'm interested in a frequency (freq) of a particular cell type which was measured longitudinal in patients (p) and control group (c). In addition, each sample was measured four times (repeat) with a possible factor influencing the sensitivity (gated).
Here my data frame:
ID freq day repeat group gated 1 0.1 1 1 c 10000 1 0.15 1 2 c 12000 1 0.2 1 3 c 50000 1 0.1 1 4 c 12000 1 0.5 12 1 c 12000 1 0.1 12 2 c 50000 1 0.2 12 3 c 100000 1 0.4 12 4 c 70000 1 0.2 5 1 p 15000 2 0.25 5 2 p 6000 2 . 2 .
So I could write a model with a fixed effects for day and group and their interaction.
lme(freq ~ day*group, random = ~day | ID data=frame)
I'm expecting possible effect of "gated" on the frequency. I don't know how to include the fact that I have four measures from the same sample and an effect of the variable "gated" on the frequency.
I'm appreciate any help, and apologize in case I have not read carefully the available documentation.
Frank -- Frank Mattes e-mail: [EMAIL PROTECTED] Department of Virology fax 0044(0)207 8302854 Royal Free Hospital and tel 0044(0)207 8302997 University College Medical School London
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