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

Data originally from John Nelson (1961) "The Nature of Wheat Lipids
and Their Role in Flour Deterioration, Ph. D. disseration, Univ. of
Minnesota, St. Paul, MN (tables 16 and 17).

The response is the fat) acidity (in mg KOH/100 g flour) of two kinds
of flour subjected to various treatments and held for various storage
times.  Column 1 is the fat acidity.  Column 2 indicates which of 11
different extraction methods was applied to the sample.  Column 3
indicates the storage time in weeks (0, 3, 6, 9, 15, 21) for the 6 levels.
Column 4 is the type of flour (1=Patent, 2=First Clear).