Poison Experiment

Keywords: factorial experiment, transformation, variance modelling

Description

The data give the survival times (in 10 hour units) in a 3 x 4 factorial experiment, the factors being (a) three poisons and (b) four treatments. Each combination of the two factors is used for four animals, the allocation to animals being completely randomized.

Download

Data File (tab-delimited text)

Source

Box, G. E. P., and Cox, D. R. (1964). An analysis of transformations (with Discussion). J. R. Statist. Soc. B, 26, 211-252.

Aitkin, M. (1987). Modelling variance heterogeneity in normal regression using GLIM. Appl. Statist., 36, 332-339.

Smyth, G. K., and Verbyla, A. P. (1999). Adjusted likelihood methods for modelling dispersion in generalized linear models. Environmetrics 10, 696-709. (Abstract - Zipped PostScript)

Analysis

Box and Cox used this data to illustrate power transformation of the response. They found that the reciprocal transformation is indicated.
Aitkin used the data to illustrate variance heterogeneity.
Smyth and Verbyla showed that untransformed responses can be modelled with a quartic mean-variance relationship.