agridat (version 1.8.1)

gilmour.slatehall: Slate Hall Farm 1978

Description

Yields for a trial at Slate Hall Farm in 1978.

source

Arthur R Gilmour and Brian R Cullis and Arunas P Verbyla (1997). Accounting for natural and extraneous variation in the analysis of field experiments. Journal of Agricultural, Biological, and Environmental Statistics, 2, 269-293.

Details

The trial was a balanced lattice with 25 varieties in 6 replicates. The plot size was 1.5 meters by 4 meters, so the total area was 15 x 1.5 meters by 10 x 4 meters. The 'rep' labels are arbitrary (no rep labels appeared in the source data). Each row within a rep is an (incomplete) block.

Examples

dat <- gilmour.slatehall

desplot(yield ~ col * row, dat, num=gen, out1=rep, main="gilmour.slatehall")

# Model 4 of Gilmour et al 1997
require(asreml)
dat <- transform(dat, xf=factor(col), yf=factor(row))
dat <- dat[order(dat$xf, dat$yf), ]
m4 <- asreml(yield ~ gen + lin(row), data=dat,
             random = ~ dev(row) + dev(col),
             rcov = ~ ar1(xf):ar1(yf))
coef(m4)$fixed[1] # linear row
# [1] 31.72252 # (sign switch due to row ordering)
summary(m4)$varcomp
#      Effect  Estimate   Std Err Z Ratio Con
#    dev(row) 20290     10260         2   Pos
#    dev(col)  2519      1959         1.3 Pos
#  R!variance 23950      4616         5.2 Pos
#    R!xf.cor     0.439     0.113     3.9 Unc
#    R!yf.cor     0.125     0.117     1.1 Unc
plot(variogram(m4))