Description Format Details Source References Examples

Yields from treatment for mildew control

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

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.

Norman Draper and Irwin Guttman (1980).
Incorporating Overlap Effects from Neighboring Units into Response
Surface Models.
*Appl Statist*, 29, 128–134.
http://doi.org/10.2307/2986297

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | ```
data(jenkyn.mildew)
dat <- jenkyn.mildew
require(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")
``` |

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