Split-plot barley variety trial with fungicide treatments

Description

Split-plot barley variety trial with fungicide treatments.

Format

A data frame with 560 observations on the following 6 variables.

yield

Yield, tonnes/ha

block

Block factor, 4 levels

gen

Genotype factor, 70 levels

fung

Fungicide factor, 2 levels

row

Row

bed

Bed (column)

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).

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.

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data(durban.splitplot)
dat <- durban.splitplot

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

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

## Not run: 
# Figure 6 - field trend
require(gam)
m2lo <- gam(yield ~ gen*fung + lo(row, bed, span=.082), data=dat)
new2 <- expand.grid(row=unique(dat$row), bed=unique(dat$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")

# Table 5, variance components.  Table 6, F tests
require(asreml)
dat <- transform(dat, rowf=factor(row), bedf=factor(bed))
dat <- dat[order(dat$rowf, dat$bedf),]
m2a2 <- asreml(yield ~ gen*fung, random=~block/fung+units, data=dat,
               rcov=~ar1v(rowf):ar1(bedf))
m2a2 <- update(m2a2)

require(lucid)
vc(m2a2)
##                effect component std.error z.ratio constr
##       block!block.var 0.0000001        NA      NA  bound
##  block:fung!block.var 0.01207    0.01513      0.8    pos
##       units!units.var 0.02463    0.002465    10      pos
##            R!variance 1                NA      NA    fix
##            R!rowf.cor 0.8836     0.03647     24    uncon
##            R!rowf.var 0.1262     0.04432      2.8    pos
##            R!bedf.cor 0.9202     0.02847     32    uncon

anova(m2a2)

## End(Not run)

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