agridat (version 1.16)

little.splitblock: Split-block experiment of sugar beets

Description

Split-block experiment of sugar beets.

Usage

data("little.splitblock")

Format

A data frame with 80 observations on the following 6 variables.

row

row

col

column

yield

sugar beet yield, tons/acre

harvest

harvest date, weeks after planting

nitro

nitrogen, pounds/acre

block

block

Details

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.

References

None.

Examples

# NOT RUN {
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
if(require(desplot)){
  desplot(yield ~ col*row, data=dat,
          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(FALSE){
  library(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)

# }