R: Horseshoe Crab Data

crabs {glm2} | R Documentation

## 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.

[Package glm2 version 1.1.3 Index]