Author: Rolf Tueschen
Date: 13:34:07 09/25/02
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On September 25, 2002 at 15:45:44, GuyHaworth wrote: > >Rolf, > >I sympathise with your confusion, but I regret that your conclusions are >incorrect. > >I heard of the 3-door scenario some years ago and was convinced that there was >no advantage in switching. > >However, I was wrong then. The explanation given is perfectly correct. Suppose >you choose a door - let's call it 'A': the chance the car is there is 1/3. The >show host then proves that the car is not behind another door - let's call it >'B'. > >So where's the remaining 2/3 probability? It's sitting behind door 'C'. > >Why does this seem odd. Because 'C' isn't a physical door, fixed before the car >is driven in. Had the car been put behind the physical door, labelled 'B' >above only temporarily, the host would have chosen the other door the contestant >did not choose. > > >If you still think it's 50/50, I would be happy for you to offer me those odds >as the bookmaker and I would employ the 'switch strategy' throughout. Over 3N >trials, I would expect to lose N times and win 2N times, a gain of N. At $1 a >trial, what N would you care to specify? > >[ When navigating in offshore races, if the crew insist that I have my facts >wrong, I pretty quickly ask them to put their money on the table. It works. ] > >g Not really, Guy. :) You fall into the Marilyn trap too. Not a big accident as such but simply wrong. NB when you begin to enjoy the coming routine, you are already way off the line of my argument. Because there is _no_ future after the unique event for the individual candidate. Of course with such a future of n>1 you were right. But I was interested in the n=1 cases. BTW I take for granted that you know that even 1/3 to 2/3 doesn't mean that it's impossible for the 1/3 to win 15 times in a row... :) Just take a look into the maths of roulette. The bank is always winning. If its budget is high enough. <g> Since you have some experience with bookmakers and money in general, what would you say, could my odds grow into heavens if people once realised that I'm a new say Einstein, Pascal or Fermat, take any name you want...? :) Rolf Tueschen
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