crabs {glm2}

Horseshoe Crab Data

Description

This data set is derived from Agresti (2007, Table 3.2, pp.76-77). It gives 4 variables for each of 173 female horseshoe crabs. Also provided are two random samples of the data with replacement, which are useful for illustrating the convergence properties of glm and glm2.

Usage

data(crabs)

Format

A data frame with 173 observations on the following 6 variables:

Satellites

number of male partners in addition to the female's primary partner

Width

width of the female in centimeters

Dark

a binary factor indicating whether the female has dark coloring (yes or no)

GoodSpine

a binary factor indicating whether the female has good spine condition (yes or no)

Rep1

a random sample with replacement from 1:173

Rep2

a second random sample with replacement from 1:173

Details

The variables Dark and GoodSpine are derived from the raw data. In the notation of Table 3.2 of Agresti (2007), Dark = yes corresponds to C>3 and GoodSpine = yes corresponds to S<3. The two random samples Rep1 and Rep2 can be used to provide random samples with replacement from the full data set. These two random samples are useful for illustrating the convergence properties of glm and glm2; see examples in the help documentation for glm2.

References

Agresti, A. (2007) An Introduction to Categorical Data Analysis (2nd ed.). Hoboken, NJ: Wiley.