jansen.apple {agridat} | R Documentation

## Infestation of apple shoots by apple canker.

### Description

Infestation of apple shoots by apple canker.

### Usage

    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.

### 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. http://doi.org/10.1111/j.1467-9574.1993.tb01414.x

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

### References

None.

### Examples

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

    require(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")

    ## Not run:
      require(lme4)
      # Tentative model.  Needs improvement.
      m1 <- glmer(cbind(y,n-y) ~ gen + factor(inoculum) + (1|block),
                  data=dat, family=binomial)
      summary(m1)

    ## End(Not run)

[Package agridat version 1.16 Index]