agridat (version 1.12)

besag.bayesian: Spring barley in United Kingdom

Description

An experiment with 75 varieties of barley, planted in 3 reps.

Format

A data frame with 225 observations on the following 4 variables.

col

Column (also blocking factor)

row

Row

yield

Yield

gen

Variety factor

Details

RCB design, each column is one rep.

References

Davison, A. C. (2003). Statistical Models. Cambridge University Press. Pages 534-535.

Examples

# NOT RUN {
data(besag.bayesian)
dat <- besag.bayesian

# Yield values were scaled to unit variance
var(dat$yield, na.rm=TRUE)

# Besag Fig 2. Reverse row numbers to match Besag, Davison
dat$rrow <- 76 - dat$row
require("lattice")
xyplot(yield ~ rrow|col, dat, layout=c(1,3), type='s',
       main="besag.bayesian")

# }
# NOT RUN {
  # Use asreml to fit a model with AR1 gradient in rows
  require(asreml)
  dat <- transform(dat, cf=factor(col), rf=factor(rrow))
  m1 <- asreml(yield ~ -1 + gen, data=dat, random=~ar1v(rf))

  # Visualize trends, similar to Besag figure 2.
  dat$res <- resid(m1)
  dat$geneff <- coef(m1)$fixed[as.numeric(dat$gen)]
  dat <- transform(dat, fert=yield-geneff-res)
  xyplot(geneff ~ rrow|col, dat, layout=c(1,3), type='s',
         main="Variety effects", ylim=c(5,15 ))
  xyplot(fert ~ rrow|col, dat, layout=c(1,3), type='s',
         main="Fertility", ylim=c(-2,2))
  xyplot(res ~ rrow|col, dat, layout=c(1,3), type='s',
         main="Residuals", ylim=c(-4,4))
# }
# NOT RUN {
# }