agridat (version 1.23)

allcroft.lodging: Multi-environment trial of cereal with lodging data

Description

Percent lodging is given for 32 genotypes at 7 environments.

Format

A data frame with 224 observations on the following 3 variables.

env

environment, 1-7

gen

genotype, 1-32

y

percent lodged

Details

This data is for the first year of a three-year study.

Used with permission of Chris Glasbey.

Examples

if (FALSE) {

library(agridat)
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

libs(lattice)
dotplot(env~y|gen, dat, as.table=TRUE,
        xlab="Percent lodged (by genotype)", ylab="Variety",
        main="allcroft.lodging")

# Tobit model
libs(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)

}