little finger theory would therefore be pretty sure to allege
that the amputations were spreading cancer and lunacy. The
vaccination controversy is full of such contentions. So is the
controversy as to the docking of horses' tails and the cropping
of dogs' ears. So is the less widely known controversy as to
circumcision and the declaring certain kinds of flesh unclean by
the Jews. To advertize any remedy or operation, you have only to
pick out all the most reassuring advances made by civilization,
and boldly present the two in the relation of cause and effect:
the public will swallow the fallacy without a wry face. It has no
idea of the need for what is called a control experiment. In
Shakespear's time and for long after it, mummy was a favorite
medicament. You took a pinch of the dust of a dead Egyptian in a
pint of the hottest water you could bear to drink; and it did you
a great deal of good. This, you thought, proved what a sovereign
healer mummy was. But if you had tried the control experiment of
taking the hot water without the mummy, you might have found the
effect exactly the same, and that any hot drink would have done
as well.


BIOMETRIKA

Another difficulty about statistics is the technical difficulty
of calculation. Before you can even make a mistake in drawing
your conclusion from the correlations established by your
statistics you must ascertain the correlations. When I turn over
the pages of Biometrika, a quarterly journal in which is recorded
the work done in the field of biological statistics by Professor
Karl Pearson and his colleagues, I am out of my depth at the