agridat (version 1.23)

jenkyn.mildew: Yields from treatment for mildew control

Description

Yields from treatment for mildew control

Format

A data frame with 38 observations on the following 4 variables.

plot

plot number

trt

treatment factor, 4 levels

block

block factor, 9 levels

yield

grain yield, tons/ha

Details

There were four spray treatments: 0 (none), 1 (early), 2 (late), R (repeated).

Each treatment occurs once between each of the 9 ordered pairs of the other treatments.

The first and last plot are not assigned to a block.

References

Maria Durban, Christine Hackett, Iain Currie. Blocks, Trend and Interference in Field Trials.

Examples

if (FALSE) {

library(agridat)
data(jenkyn.mildew)
dat <- jenkyn.mildew

libs(lattice)
bwplot(yield ~ trt, dat, main="jenkyn.mildew", xlab="Treatment")

# Residuals from treatment model show obvious spatial trends
m0 <- lm(yield ~ trt, dat)
xyplot(resid(m0)~plot, dat, ylab="Residual",
       main="jenkyn.mildew - treatment model")

# The blocks explain most of the variation
m1 <- lm(yield ~ trt + block, dat)
xyplot(resid(m1)~plot, dat, ylab="Residual",
       main="jenkyn.mildew - block model")

}