Stochasticity

n. the property of being randomly determined so that one’s behavior can be analyzed statistically but not predicted precisely.

Today’s definition, which was reworded from the O.E.D., was the name of the most recent episode of N.P.R.’s wonderful show Radio Lab.  There seem to be plenty of synonyms for chance or randomness, but what I like about this one is the idea that there is a certain predictability to randomness.  As the episode of Radio Lab suggests, unlikely events occur quite predictably in a random world.  Here is a short story from the show to emphasize the point:

They described an experiment where the tester had two groups.  Group A was to flip a coin one hundred times and record the events.  Group B was to imagine flipping a coin one hundred time and record the imagined results.  When both groups finished, they wrote their results on the board (T, H, H, T, H, T, T, etc.).  The results of the two, at a layman’s glance, apparently looked quite similar.  The tester, however, immediately recognized which results belonged to which group.  The reason? Group A, early on, had a string of seven straight tails.  No one would imagine such a result, but statistically, there is a pretty good chance that it would happen (about one out of six if you flip a coin one hundred times and, I imagine, one out of three if you accepts seven straight heads as well).

This reminds me of the math equation to determine the odds that two people will share the same birthday.  If memory serves me correctly, it only takes a room of thirty-five people to make it more likely than not that two will share the same day.  I tested this in the days when I taught classes that large and it worked.

Hmm…is there a word for something that appears unlikely but is actually quite likely?

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