agridat (version 1.27)

versteeg.maize: Maize and pigeon pea criss-cross trial in Benin

Description

Maize and pigeon pea criss-cross trial in Benin

Usage

data("versteeg.maize")

Format

A data frame with 150 observations on the following 4 variables.

farm

farm

system

cropping system

gen

maize hybrid

yield

yield t/ha

Details

Experiment conducted in 1988 on 25 farms.

Trial objectives: Compare 3 genotypes & compare two cropping systems. Within each trial, a block 30m x 20m was divided into 3 plots for genotypes. The block was also divided into 2 portions for the cropping system. This is called a "strip-plot", "split-block" or "criss-cross design".

Data provenance: Scanned by iPhone from page 114. Checked by K.Wright.

References

Mutsaers, H. J. W., G. K. Weber, P. Walker, and N.M. Fischer (1997) A field guide for on-farm experimentation. https://archive.org/details/isbn_9781311258/page/n3/mode/1up

Examples

if (FALSE) {
library(agridat)
data(versteeg.maize)
dat <- versteeg.maize

dat <- transform(dat, farm=as.factor(farm),
 gen=as.factor(gen), system=as.factor(system))

# anova of Versteeg page 115
# plots are different sizes, so we have to manually
# specify the error terms for testing
m1 <- aov(yield ~ 1 + farm + gen + system + gen:system +
 Error(gen:farm + system:farm), data=dat)
summary(m1)

libs(dplyr)
d1 <- summarize(dat, mn=mean(yield), .by=farm)
dat <- left_join(dat, d1)

# stability analysis, figure 1 of Versteeg, page 119
libs(lattice)
xyplot(yield~mn, data=dat, groups=gen, type=c('p','r'))
}