Split-block experiment of sugar beets
Split-block experiment of sugar beets.
data("little.splitblock")A data frame with 80 observations on the following 6 variables.
rowrow
colcolumn
yieldsugar beet yield, tons/acre
harvestharvest date, weeks after planting
nitronitrogen, pounds/acre
blockblock
Four rates of nitrogen, laid out as a 4x4 Latin-square experiment.
Within each column block, the sub-plots are strips (across 4 rows) of 5 different harvest dates.
The use of sub-plots a s strips necessitates care when determining the error terms in the ANOVA table.
Note, Little has yield value of 22.3 for row 3, column I-H3. This data uses 23.3 in order to match the marginal totals given by Little.
Thomas M. Little, F. Jackson Hills. (1978) Agricultural Experimentation
None.
## Not run:
library(agridat)
data(little.splitblock)
dat <- little.splitblock
# Match marginal totals given by Little.
## sum(dat$yield)
## with(dat, tapply(yield,col,sum))
## with(dat, tapply(yield,row,sum))
# Layout shown by Little figure 10.2
libs(desplot)
desplot(dat, yield ~ col*row,
out1=block, out2=col, col=nitro, cex=1, num=harvest,
main="little.splitblock")
# Convert continuous traits to factors
dat <- transform(dat, R=factor(row), C=factor(block),
H=factor(harvest), N=factor(nitro))
if(0){
libs(lattice)
xyplot(yield ~ nitro|H,dat)
xyplot(yield ~ harvest|N,dat)
}
# Anova table matches Little, table 10.3
m1 <- aov(yield ~ R + C + N + H + N:H +
Error(R:C:N + C:H + C:N:H), data=dat)
summary(m1)
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