marie-lou.lefrancois at bvcentre.ca
2008-Aug-13 17:40 UTC
[R] How to test for a random effect in a repeated measures analysis using anova.mlm ?
Dear ?R? masters, I am trying to conduct an ANOVA with repeated measures using the command anova.mlm for data structured according to a Randomized Block Design. I would like to account for a random effect but cannot find a way to incorporate it in the analysis. NB. I tried using the argument ?M? to define the outer projection (block), I get the message that length differs. ?response? is the dependent variable (3 years of heights measurements, merged with cbind). ?estab? is a factor with 3 levels (whether trees were planted, seeded or naturally established). I would like to include ?block? as a random effect. I would like to keep the structure of the response variable (so I don?t get an output with a test for each year: this is what happens when I use ?lme? or ?aov?). This is the code I am using: First, fit linear models: estabfit<-lm(response~estab) timefit<-lm(response~1) Then test the effect of the factor ?estab? anova.mlm(timefit,estabfit,M=~1). How do I integrate ?block?? I was inspired by: http://tolstoy.newcastle.edu.au/R/help/05/11/15744.html Thank you so much for your help! Cheers Marie-lou Lefrancois