jenkyn.mildew {agridat} | R Documentation

## 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.

### Source

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

### References

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

### Examples

    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")

[Package agridat version 1.16 Index]