glmtoolbox (version 0.1.12)

orobanche: Germination of Orobanche Seeds

Description

These data arose from a study of the germination of two species of Orobanche seeds (O. aegyptiaca 75 and O. aegyptiaca 73) grown on 1/125 dilutions of two different root extract media (cucumber and bean) in a 2×2 factorial layout with replicates. The data consist of the number of seeds and germinating seeds for each replicate. Interest is focused on the possible differences in germination rates for the two types of seed and root extract and whether there is any interaction.

Usage

data(orobanche)

Format

A data frame with 21 rows and 4 variables:

specie

a factor indicating the specie of Orobanche seed: O. aegyptiaca 75 ("Aegyptiaca 75") and O. aegyptiaca 73 ("Aegyptiaca 73").

extract

a factor indicating the root extract: cucumber ("Cucumber") and bean ("Bean").

seeds

a numeric vector indicating the total number of seeds.

germinated

a numeric vector indicating the number of germinated seeds.

References

Crowder M.J. (1978) Beta-binomial anova for proportions. Journal of the Royal Statistical Society. Series C (Applied Statistics) 27:34-37.

Hinde J., Demetrio C.G.B. (1998) Overdispersion: Models and estimation. Computational Statistics & Data Analysis 27:151-170.

Examples

data(orobanche)
out <- aggregate(cbind(germinated,seeds) ~ extract + specie, data=orobanche, sum)
dev.new()
barplot(100*germinated/seeds ~ extract + specie, beside=TRUE, data=out, width=0.3,
        col=c("yellow","blue"), xlab="Specie", ylab="% of germinated seeds")
legend("topleft",c("Bean","Cucumber"),fill=c("yellow","blue"),title="Extract",bty="n")