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BGonline.org Forums
How do you weigh risk vs. reward here?
Posted By: kruidenbuiltje In Response To: How do you weigh risk vs. reward here? (Klaus Evers)
Date: Friday, 26 July 2013, at 6:17 p.m.
Hi,
On average the pipcount will be 84-100 after white's next move. A little correction for the second checker on the 1-point: 86-100. Racing chances are about 83%. White gets an indirect shot now (4/36 = 11%), and probably one later. The chance blue misses both indirect shots is 32/36 ^2 = 79%. White's hitting chances are 21%. But since blue might close the 2-point (42,D2,D4) or pick and pass (41,21,D1), the hitting chances are a little less, say 19%. Of course we should not think that white will get all his race-chances, blue will get some more point or pick and pass chances.
But let's say white gets 19% hits and 10% race of the non-hits = 27%. The risk of hitting loose is 11/36 + (non-cover or pass to 1-point) * 11/36 = about 15/36 = 41%. Gammon chance with 1 closed-out and 6 crossovers is about 35%.
Now let's compare blue gets 0,73 - 0,27 = 0,46 equity (safe) or 0,59 + 0,20 (gammons) - 0,41 = 0,38 equity (risk).
So it seems the 10%-rule might be right here.
Let's see the different influences in the formula.
a) if the pipcount were 10%: 90-100, the racing chance was: 21%, the white chance was 19% (hits) + 21% of non-hits = 36%
the safe equity would be 0,64 - 0,36 = 0,28... the risky would be better.
b) if white had 3 extra outfield crossovers giving 50% gammons by a close-out, then the risky part would say:
0,59 + 0,30 (gammons) - 0,41 = 0,48 .... the risky would be better.
c) if we had 3 instead of two cover or pass numbers making the risk of hitting loose 13/36 = 36%, then the risky part would say:
0,64 + 0,22 (gammons) - 0,36 = 0,50.... the risky would be better.
d) I have not taken into account blue's return-chances after the possible white hit, in your position it is only 2/36 (26 from the bar)
so its not enough to take into account, but what if it were 6/36 i guess that would make the risky option abut equal.
e) if blue had the cube he would better play safe, since after 10/4 and white misses he could double white out.
The second indirect shot and the white race-wins would then never occur.
Conclusion:
The 10% pip-rule is a very rough indicator, other aspects are cover numbers, outfield crossovers and blue returnshots. Cube ownership is very influential.
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