search for: sigma_pop

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2007 Oct 26
1
2-way Factorial with random factors
..., I typed: fm3 <- lmer(fruto~(1|pop) + (1|spp) + (1|pop:spp), data=p1) During calculations I get an error which indicates that the variance components for pop and pop:spp are almost zero. The summary output presents variance components that do not resemble the manually estimated values (eg. sigma_pop = 3650 vs sigma_pop(reml) = 7840). If I conduct the analysis in SAS, with GLM and the random option, I get correct estimates of variance components. After reading a couple of help files, it looks like I need a fixed component, which I don?t know how to code (dummy coding?). My specific questio...