jansen.strawberry {agridat} | R Documentation

## Ordered disease ratings on strawberry crosses.

### Description

Ordered disease ratings on strawberry crosses.

### Usage

    data("jansen.strawberry")

### Format

A data frame with 144 observations on the following 5 variables.

`male`

  male parent

`female`

  female parent

`block`

  block

`category`

  disease damage, `C1` < `C2` < `C3`

`count`

  number of plants in each category

### Details

In strawberries, red core disease is caused by a fungus, Phytophtora fragariae. This experiment evaluated different populations for damage caused by red core disease.

There were 3 male strawberry plants and 4 DIFFERENT female strawberry plants that were crossed to create 12 populations. Note: Jansen labeled the male parents 1,2,3 and the female parents 1,2,3,4. To reduce confusion, this data labels the female parents 5,6,7,8.

The experiment had four blocks with 12 plots each (one for each population). Plots usually had 10 plants, but some plots only had 9 plants. Each plant was assessed for damage from fungus and rated as belonging to category C1, C2, or C3 (increasing damage).

### Source

J. Jansen, 1990. On the statistical analysis of ordinal data when extravariation is present. Applied Statistics, 39, 75-84, Table 1. http://doi.org/10.2307/2347813

Used with permission of Hans Jansen.

### Examples

    data(jansen.strawberry)
    dat <- jansen.strawberry
    dat <- transform(dat, category=ordered(category, levels=c('C1','C2','C3')))

    dtab <- xtabs(count ~ male + female + category, data=dat)
    ftable(dtab)

    mosaicplot(dtab,
               color=c("lemonchiffon1","lightsalmon1","indianred"),
               main="jansen.strawberry disease ratings",
               xlab="Male parent", ylab="Female parent")

    if(require(MASS) & require(vcd)){
      # Friendly suggests a minimal model is [MF][C]
      # m1 <- loglm( ~ 1*2 + 3, dtab) # Fails, only with devtools
      # mosaic(m1)
    }

[Package agridat version 1.16 Index]