Marcelo Laia
2009-Nov-22 14:42 UTC
[R] Repeated measures unbalanced in a split-split design
Hi, I have a experiment with block, plots, sub-plots, and sub-sub-plots with repeated measures and 3 factors (factorial design) when we have been observed diameter (mm), high (cm) and leaves number (count). However, we don't have one treatment in one factor, so, my design is unbalanced. On a previous message here, a friend tell me that "It appears to me that your design is a split-split plot with repeated measures at the split-split plot level. Because you have multiple sizes of experimental unit (blocks, plots and sub-plots), you have a different random error term at each size of unit, so you have to analyze it as a mixed-effects model. For the diameter and height measurements, you can probably get away with using normal errors, but for the counts, you may well have to use a generalized linear mixed model." So, I am trying to analyze my data with car package. I have: time (days after germination) -> 4 levels (38, 53, 73, 85) Hormone -> 2 levels (SH, CH) on sub-plots Block -> 4 blocks Treatment -> 6 levels (1, 2, 3, 4, 5, and 6) on sub-sub-plots Plant -> subjects I measured Diameter (mm), Height (cm), HD (height/diameter), and Number of Leaves (count) at each time point. But, plant can be died and I got NAs. However, Treatment 6 (control) is only present on SH sub-plots. It isn't present on CH sub-plots. I try this model: idata.Cana <- data.frame(Time=factor(c(38,53,73,85))) idata.Cana mod.Cana <- lm(cbind(Diameter.38, Diameter.53, Diameter.73, Diameter.85) ~ Treatment*Hormone, data=marcelo.subset) mod.Cana Call: lm(formula = cbind(Diameter.38, Diameter.53, Diameter.73, Diameter.85) ~ Treatment * Hormone, data = marcelo.subset) Coefficients: Diameter.38 Diameter.53 Diameter.73 Diameter.85 (Intercept) 1.24000 1.35750 1.99375 2.31000 Treatment2 -0.31625 -0.14250 0.07500 -0.13875 Treatment3 -0.19250 -0.01500 -0.20875 -0.36875 Treatment4 -0.35375 -0.08500 -0.22750 -0.27125 Treatment5 -0.29125 0.04875 -0.14375 -0.26375 Treatment6 -0.00125 -0.25750 -0.81125 -0.77750 HormoneSH -0.30875 -0.08875 0.31500 0.07000 Treatment2:HormoneSH 0.19875 0.11250 -0.44500 -0.24875 Treatment3:HormoneSH 0.15375 0.01875 -0.12125 0.07000 Treatment4:HormoneSH 0.28000 -0.04250 -0.41750 -0.38750 Treatment5:HormoneSH 0.40875 -0.11125 -0.17750 -0.05125 Treatment6:HormoneSH NA NA NA NA av.Cana <- Anova(mod.Cana, idata=idata.Cana, idesign= ~ as.factor(Idade)) Erro em solve.default(crossprod(model.matrix(mod))) : rotina Lapack dgesv: sistema ? exatamente singular How I model my data to analyze it with this unbalanced design? How I could use the block factor on model? Or it is not necessary? And sub-plots? Please, here you could find my design http://www.divshare.com/download/9431636-e0c and here you could find a subset of my data http://www.divshare.com/download/9456640-fd7 Thank you very much! -- Marcelo Luiz de Laia Universidade do Estado de Santa Catarina UDESC - www.cav.udesc.br Lages - SC - Brazil Linux user number 487797