Forum Archive :
Match Play at 2-away/2-away
Minimum game winning chances to double
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Tom Penney wrote:
> Julian is correct. When both players are 2 points away from wining a
> match it is correct to double with anything over 50% chance of winning ...
A common misconception. Actually you don't need to be a favorite in the
game to double. Consider the following bearoff position:
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X X|
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X's cubeless probabiity of winning is 39.9%, so that is his probability of
winning the match if he doubles.
If he doesn't double, he gets a 70% match winning probability if he rolls
one of the 8 numbers that bear off, and a 30% chance if he rolls one of the
other 28 (because he should drop his opponent's cube, having only a 25% or
less cpw.)
So his total mwp. would be 8/36*70% + 28/36*30% = 38.9%, which is less
than what he would get by doubling.
This situation turns out to be fairly typical. In a race it is usually
right to be doubling with a cpw around 40%. In a LONG race, you may need as
much as 41% or 42% to double.
-- Walter Trice
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Match Play at 2-away/2-away
- Basic strategy (Darse Billings, Feb 1995)
- Counterexample? (Jim Williams+, Mar 1998)
- Do you need an advantage to cube? (Keene Marin+, Feb 2006)
- Double immediately? (Chuck Bower, Oct 1998)
- Ever too good to double? (Kit Woolsey, July 1995)
- Minimum game winning chances to double (Walter Trice, Mar 1999)
- Practical strategy (Walter Trice, July 1995)
- Practical strategy (Albert Steg+, Feb 1995)
- Proof for doubling immediately (Robert Koca+, May 1994)
- Proof of doubling with market losers (Walter Trice+, July 2001)
- Sample game (Ron Karr, Dec 1996)
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