A data set from Oehlert (2000) \emph{A First Course in Design and
Analysis of Experiments}, New York: W. H. Freeman.

Data originally from Simpson, J., A.~Olsen, and J.~C. Eden (1975). ``A
{B}ayesian analysis of a multiplicative treatment effect in weather
modification.'' {\em Technometrics\/}~{\em 17}, 161--166.

Col 1 is treatment (1 = nonseeded, 2 = seeded)
col 2 gives rainfall in acre feet