agridat (version 1.16)

kempton.rowcol: Wheat row-column experiment

Description

Wheat yields of 35 genotypes, 2 reps, planted in a row-column design. Two plots are missing.

Format

A data frame with 68 observations on the following 5 variables.

rep

replicate factor, 2 levels

row

row

col

column

gen

genotype factor, 35 levels

yield

yield

Details

Included to illustrate REML analysis of a row-column design.

Examples

# NOT RUN {
data(kempton.rowcol)
dat <- kempton.rowcol
dat <- transform(dat, rowf=factor(row), colf=factor(col))

if(require(desplot)){
  desplot(yield~col*row|rep, dat,
          num=gen, out1=rep, # unknown aspect
          main="kempton.rowcol")
}


# }
# NOT RUN {
  # Model with rep, row, col as random.  Kempton, page 62.
  # Use "-1" so that the vcov matrix doesn't include intercept
  require(lme4)
  m1 <- lmer(yield ~ -1 + gen + rep + (1|rep:rowf) + (1|rep:colf), data=dat)
  
  # Variance components match Kempton.
  print(m1, corr=FALSE)
  
  # Standard error of difference for genotypes.  Kempton page 62, bottom.
  covs <- as.matrix(vcov(m1)[1:35, 1:35])
  vars <- diag(covs)
  vdiff <- outer(vars, vars, "+") - 2 * covs
  sed <- sqrt(vdiff[upper.tri(vdiff)])
  min(sed) # Minimum SED
  mean(sed) # Average SED
  max(sed) # Maximum SED
# }
# NOT RUN {
# }