Reference: Chambers, Cleveland, Kleiner, and Tukey. (1983). Graphical Methods for Data Analysis. Wadsworth International Group, Belmont,
CA, 351. Original Source: Simpson, Alsen, and Eden. (1975). A Bayesian analysis of a multiplicative treatment effect in weather modification.
Technometrics 17, 161-166. 
Authorization: contact authors 
Description: Rainfall from Cloud-Seeding. The rainfall in acre-feet from 52 clouds 26 of which were chosen at random and seeded with silver
nitrate.

Variables:

   rainfall --  amount of rainfall in acre-feet from a cloud
   seeded   --  S = seeded cloud, U = unseeded cloud