What is the statistical technique called.....

[birkoff]

Where you sum scientific data or dollar data and find that in the
real world its more likely to average 3 or close to that because
lots of numbers are closer to the 1 end then then the 9 end.

I use to know it, but forgot what its called. Its a way of telling
if the numbers somebody has produced are valid or just random
and made up.

Thanks!!