Format
This data frame was originally poison.data from the package
  BHH2, but as presented here has added columns; no NAs. 
  - Poison
 - Factor with three levels I, II, and III.
  - Treatment
 - Factor with four levels, A, B, C, and D.
  - Group
 - Factor with 12 levels, 1:12.
  - SurvTime
 - Numeric; survival time.
  - RateSurvTime
 - Numeric; inverse of SurvTime
  - RankRateSurvTime
 - Numeric; 
RateSurvTime scores have
  been converted to ranks, and then rescaled to have the same median as and
  a spread comparable to RateSurvTime 
 
Source
Box, G. E. P. and D. R. Cox, An Analysis of Transformations (with
  discussion), Journal of the Royal Statistical Society, Series B, Vol. 26,
  No. 2, pp. 211 - 254.