Ordered disease ratings of 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).

Used with permission of Hans Jansen.

Source

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

Examples

if (FALSE) { # \dontrun{

library(agridat)

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")

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

} # }