hcrabs {rsq}

Satellites of Female Horseshoe Crabs

Description

Recorded are the numbers of male satellites, and other characteristics of 173 female horseshoe crabs.

Usage

data("hcrabs")

Format

A data frame with 173 observations on the following 5 variables.

color

the female crab's color, coded 1: light; 2: medium light; 3: medium; 4: medium dark; 5: dark. Not all of these colors appear.

spine

the female crab's spine condition, coded 1: both good; 2: one worn or broken; 3: both worn or broker.

width

the female crab's carapace width (cm).

num.satellites

the number of satellite males.

weight

the female crab's weight (kg).

Details

A nesting female horseshoe crab may have male crabs residing nearby, called satellites, besides the male crab residing in her nest. Brockmann (1996) investigated factors (including the female crab's color, spine condition, weight, and carapace width) which may influence the presence/obsence of satellite males. This data set has been discussed by Agresti (2002).

Author(s)

Dabao Zhang, Department of Statistics, Purdue University

Source

Agresti, A. (2012). An Introduction to Categorical Data Analysis, 3rd edition. Wiley: New Jersey.

References

Brockmann, H. J. (1996). Satellite male groups in horseshoe crabs. Limulus polyphemus. Ethology, 102: 1-21.

See Also

rsq, rsq.partial, pcor, simglm.

Examples

data(hcrabs)
summary(hcrabs)
head(hcrabs)

attach(hcrabs)
y <- ifelse(num.satellites>0,1,0)
bnfit <- glm(y~color+spine+width+weight,family=binomial)
rsq(bnfit)
rsq(bnfit,adj=TRUE)
rsq.partial(bnfit)

quasips <- glm(num.satellites~color+spine+width+weight,family=quasipoisson)
rsq(quasips)
rsq(quasips,adj=TRUE)
rsq.partial(quasips)