R Dataset / Package MASS / snails

On this R-data statistics page, you will find information about the snails data set which pertains to Snail Mortality Data. The snails data set is found in the MASS R package. You can load the snails data set in R by issuing the following command at the console data("snails"). This will load the data into a variable called snails. If R says the snails data set is not found, you can try installing the package by issuing this command install.packages("MASS") and then attempt to reload the data with the library() command. If you need to download R, you can go to the R project website. You can download a CSV (comma separated values) version of the snails R data set. The size of this file is about 1,835 bytes.

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.

Dataset imported from https://www.r-project.org.

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