Infestation of apple shoots by apple canker.

data("jansen.apple")

Format

A data frame with 36 observations on the following 5 variables.

inoculum: inoculum level
gen: genotype/variety
block: block
y: number of inoculations developing canker
n: number of inoculations

Details

Shoots of apple trees were infected with fungus Nectria galligena, which may cause apple canker.

The incoulum density treatment had 3 levels, measured in macroconidia per ml.

There were 4 blocks.

Used with permission of J. Jansen. Electronic version supplied by Miroslav Zoric.

Source

J. Jansen & J.A. Hoekstra (1993). The analysis of proportions in agricultural experiments by a generalized linear mixed model. Statistica Neerlandica, 47(3), 161-174. https://doi.org/10.1111/j.1467-9574.1993.tb01414.x

References

None.

Examples

# \dontrun{

library(agridat)
data(jansen.apple)
dat <- jansen.apple

libs(lattice)
xyplot(inoculum ~ y/n|gen, data=dat, group=block,
       layout=c(3,1),
       main="jansen.apple",
       xlab="Proportion infected per block/inoculum",
       ylab="Inoculum level")

## libs(lme4)
## # Tentative model.  Needs improvement.
## m1 <- glmer(cbind(y,n-y) ~ gen + factor(inoculum) + (1|block),
##             data=dat, family=binomial)
## summary(m1)

# }