agridat (version 1.12)

denis.missing: Multi-environment trial with structured missing values

Description

Grain yield was measured on 5 genotypes in 26 environments. Missing values were non-random, but structured.

Format

env

Environment factor, 26 levels

gen

Genotype factor, 5 levels

yield

Yield

References

H P Piepho, (1999) Stability analysis using the SAS system, Agron Journal, 91, 154--160.

Examples

# NOT RUN {
data(denis.missing)
dat <- denis.missing

# View missingness structure
require(reshape2)
acast(dat, env~gen, value.var='yield')
require(lattice)
levelplot(yield ~ gen*env, data=dat,
          col.regions=RedGrayBlue,
          main="denis.missing - incidence heatmap")

# Stability variance (Table 3 in Piepho)
require("nlme")
m1 <- lme(yield ~ -1 + gen, data=dat, random= ~ 1|env,
          weights = varIdent(form= ~ 1|gen),
          na.action=na.omit)
svar <- m1$sigma^2 * c(1, coef(m1$modelStruct$varStruct, unc = FALSE))^2
round(svar, 2)
##          G5    G3    G1    G2
## 39.25 22.95 54.36 12.17 23.77
# }