From: utzoo!decvax!harpo!eagle!karn
Newsgroups: net.misc
Title: ESP & Elementary Probability
Article-I.D.: eagle.802
Posted: Sun Feb 27 23:37:59 1983
Received: Mon Feb 28 08:54:53 1983

Hasn't anyone taken even an elementary probability course?!

When I took one as a sophomore, our professor (who incidentally was a
gambling hobbyist and a successful blackjack card counter) related one
way to use "ESP" for fun and profit:

Take 64 [football fans | horse racing fans | whatever] who are gullible
enough to believe in ESP.  (This shouldn't be too hard.)  It is
desirable that none of the 64 know each other. Take an upcoming event
(game, race, etc) in which there is a 50-50 binary outcome of some sort
on which they can bet, and offer "free" advice to each of your 64
"clients": to the first 32, you tell them that you "sense" outcome "A",
and to the other 32, you tell them to bet on outcome "B".  After the
event, you drop the half for which you were wrong.  Now you take your
remaining 32 and split them up into two groups of 16, repeating the
above process.

After you have done this 6 times, you will have one person remaining for
which you've been right six times in a row. This person is your victim. 
You tell him that you have "shared your power" with him, FOR FREE, six
times already out of the goodness of your heart. You ask him to be fair
to you and "share the profits" (before the event, of course), and
naturally you soak him for all he's worth.

He's quite likely to go along, since the chances of your having given
him the six outcomes strictly by luck, of course, was only 1/64.

If you try this, don't tell anybody where you heard it.

Phil Karn