allcroft.lodging {agridat} | R Documentation |
Percent lodging is given for 32 genotypes at 7 environments.
A data frame with 224 observations on the following 3 variables.
env
environment, 1-7
gen
genotype, 1-32
y
percent lodged
This data is for the first year of a three-year study.
D. J. Allcroft and C. A. Glasbey, 2003. Analysis of crop lodging using a latent variable model. Journal of Agricultural Science, 140, 383–393. http://doi.org/10.1017/S0021859603003332
Used with permission of Chris Glasbey.
data("allcroft.lodging") dat <- allcroft.lodging # Transformation dat$sy <- sqrt(dat$y) # Variety 4 has no lodging anywhere, so add a small amount dat[dat$env=='E5' & dat$gen=='G04',]$sy <- .01 require(lattice) dotplot(env~y|gen, dat, as.table=TRUE, xlab="Percent lodged (by genotype)", ylab="Variety", main="allcroft.lodging") # Tobit model if(require(AER)){ m3 <- tobit(sy ~ 1 + gen + env, left=0, right=100, data=dat) # Table 2 trial/variety means preds <- expand.grid(gen=levels(dat$gen), env=levels(dat$env)) preds$pred <- predict(m3, newdata=preds) round(tapply(preds$pred, preds$gen, mean),2) round(tapply(preds$pred, preds$env, mean),2) }