Datasets for Statistical Analysis

Survival time of animals

Keywords:

survival

Categories:

generalized linear model, Tweedie model, regression, designed experiments;
biology

Description:

The data contain the survival time of animals arranged as a 3 by 4 factorial experiment.

Variables:

Poison	The poison used (three levels)
Treatment	The treatment (four levels)
Time	The survival time (in 10 hour units)

Data Quality:

There are no missing values.

Source:

Hand et al., dataset 403.

Notes:

A regression model (or analysis of variance model) with a reciprocal transform of survival time is appropriate.
The Box-Cox transformation was introduced using this dataset, the authors deciding that a reciprocal transformation of the survival time was appropriate. The equivalent Twedie model has p=4. The ml estimate of p actually is 3.85, and the Tweedie model is slightly superior (Dunn and Smyth, 2005).

References:

Box, G. E. P. and Cox, D. R. (1964). `An analysis of transformations (with discussion)' in Journal of the Royal Statistical Society Series B, 26, 211–252.

Dunn, P. K. and Smyth, G. K, (2005). Series evaluation of Tweedie exponential dispersion model densities. Statistics and Computing, 15(4), 267–280.