roots: Infection of roots by soil-borne pathogens.

In trobinj/trtools: Miscellaneous Tools for Teaching Statistics

Infection of roots by soil-borne pathogens.

Description

Roots were planted in samples in two types of soil, conducive or suppressive, infected with different densities of an inoculum. The number of infected roots was later observed. Note that there are three replicates for each combination of density and soil type.

Usage

roots

Format

A data frame with 30 observations and four variables:

soil

soil type (conducive or suppressive)

density

inoculum density (units unknown)

infected

number of infected roots

total

number of roots exposed

Note

The data are from Garthwaite et al. (2002) who use the data to motivate the complementary log-log link by assuming that the number of infections has an approximately Poisson distribution where the rate of infection is proportional to a power function of the inoculum density. They cite Gilligan (1983) as the original source for these data but note that these data are not reported there.

Source

Garthwaite, P. H., Jolliffe, I. T., & Jones, B. (2002). Statistical inference (2nd edition). Oxford, UK: Oxford University Press.

Gilligan, C. A. (1983). A test of randomness of infection by soilborne pathogens. Phytopathology, 73, 300-303.

trobinj/trtools documentation built on Jan. 3, 2025, 4:14 a.m.