snails {MASS}R Documentation

Snail Mortality Data

Description

Groups of 20 snails were held for periods of 1, 2, 3 or 4 weeks in carefully controlled conditions of temperature and relative humidity. There were two species of snail, A and B, and the experiment was designed as a 4 by 3 by 4 by 2 completely randomized design. At the end of the exposure time the snails were tested to see if they had survived; the process itself is fatal for the animals. The object of the exercise was to model the probability of survival in terms of the stimulus variables, and in particular to test for differences between species.

The data are unusual in that in most cases fatalities during the experiment were fairly small.

Usage

snails

Format

The data frame contains the following components:

Species
Snail species A (1) or B (2)
Exposure
Exposure in weeks
Rel.Hum
Relative humidity (4 levels)
Temp
Temperature, in degrees Celsius (3 levels)
Deaths
Number of deaths
N
Number of snails exposed

Source

Zoology Department, The University of Adelaide.

References

Venables, W. N. and Ripley, B. D. (1999) Modern Applied Statistics with S-PLUS. Third Edition. Springer.


[Package MASS version 7.2-33 Index]