agridat (version 1.8.1)

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.

source

Denis, J. B. and C P Baril, 1992, Sophisticated models with numerous missing values: The multiplicative interaction model as an example. Biul. Oceny Odmian, 24--25, 7--31. Used with permission of Jean-Baptists Denis.

References

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

Examples

dat <- denis.missing

# View missingness structure
require(reshape2)
acast(dat, env~gen, value.var='yield')

# Stability variance (Table 3 in Piepho)
library("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