Dear R-help,
Why can't lme cope with an incomplete whole plot when analysing a split-plot
experiment? For example:
R : Copyright 2006, The R Foundation for Statistical Computing
Version 2.3.1 (2006-06-01)
> library(nlme)
> attach(Oats)
> nitro <- ordered(nitro)
> fit <- lme(yield ~ Variety*nitro, random=~1|Block/Variety)
> anova(fit)
numDF denDF F-value p-value
(Intercept) 1 45 245.14333 <.0001
Variety 2 10 1.48534 0.2724
nitro 3 45 37.68560 <.0001
Variety:nitro 6 45 0.30282 0.9322
# Excellent! However ---
> fit2 <- lme(yield ~ Variety*nitro, random=~1|Block/Variety, subset=
+ !(Variety == "Golden Rain" & nitro == "0"))
Error in MEEM(object, conLin, control$niterEM) :
Singularity in backsolve at level 0, block 1
--
************************************************
* I.White *
* University of Edinburgh *
* Ashworth Laboratories, West Mains Road *
* Edinburgh EH9 3JT *
* Fax: 0131 650 6564 Tel: 0131 650 5490 *
* E-mail: [EMAIL PROTECTED] *
************************************************
----- End forwarded message -----
--
************************************************
* I.White *
* University of Edinburgh *
* Ashworth Laboratories, West Mains Road *
* Edinburgh EH9 3JT *
* Fax: 0131 650 6564 Tel: 0131 650 5490 *
* E-mail: [EMAIL PROTECTED] *
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