Plant scientists have developed new corn varieties that contain more 
amino acids (building blocks of protein) than normal corn.  To test 
a new corn variety as an animal food, a group of 20 1-day-old male chicks
were fed a ration containing the new corn.  A control group of another 20
chicks were fed a ration that was identical except that it contained normal
corn.  This dataset contains the weight gain in grams after 21 days for
each chick.

The variables are:

   diet      0 = normal corn,   1 = new corn
   gain      weight gain in grams

Data are from Cromwell, G.O. et al. (1968) "A comparison of the nutritive
value of opaque-2, floury-2 and normal corn for the chick," Poultry Science,
57, 840-847.  They are cited in Moore, D.S.  (1999) The Basic Practice of
Statistics, pub Freeman.