agridat (version 1.5)

durban.splitplot: Split-plot barley variety trial with fungicide treatments

Description

Split-plot barley variety trial with fungicide treatments.

Usage

data(durban.splitplot)

source

Durban, Maria and Hackett, Christine and McNicol, James and Newton, Adrian and Thomas, William and Currie, Iain. 2003. The practical use of semiparametric models in field trials, Journal of Agric Biological and Envir Stats, 8, 48-66. Retrieved from ftp://ftp.bioss.sari.ac.uk/pub/maria. Used with permission of Maria Durban.

Details

Grown in 1995-1996 at the Scottish Crop Research Institute. Split-plot design with 4 blocks, 2 whole-plot fungicide treatments, and 70 barley varieties or variety mixes. Total area was 10 rows (north/south) by 56 beds (east/west).

Examples

d2 <- durban.splitplot

# Durban 2003, Figure 2
m20 <- lm(yield~gen*fung, data=d2)
d2$resid <- m20$resid
require(lattice)
xyplot(resid~row, d2, type=c('p','smooth'))
xyplot(resid~bed, d2, type=c('p','smooth'))

# Figure 4 doesn't quite match due to different break points
coplot(resid~bed|row, data=d2, number=8,cex=.5, panel=function(x,y,...) panel.smooth(x,y,span=.4,...))

# Figure 6 - field trend
require(gam)
m2lo <- gam(yield ~ gen*fung + lo(row, bed, span=.082), data=d2)
new2 <- expand.grid(row=unique(d2$row), bed=unique(d2$bed))
new2 <- cbind(new2, gen="G01", fung="F1")
p2lo <- predict(m2lo, new=new2)
wireframe(p2lo~row+bed, new2, aspect=c(1,.5), main="Field trend")

d2 <- transform(d2, rowf=factor(row), bedf=factor(bed))
d2 <- d2[order(d2$rowf, d2$bedf),]

# Table 5, variance components.  Table 6, F tests
require(asreml)
m2a2 <- asreml(yield ~ gen*fung, random=~block/fung+units, data=d2,
rcov=~ar1v(rowf):ar1(bedf))
summary(m2a2)$varcomp
anova(m2a2)