law' of av'erages
1. a statistical principle formulated by Jakob Bernoulli to show a more or less predictable ratio between the number of random trials of an event and its occurrences.
2. Informal.the principle that, in the long run, probability as naively conceived will operate and influence any one occurrence.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.