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BGonline.org Forums
Outstanding O'Hagan Tribute!
Posted By: John O'Hagan In Response To: Outstanding O'Hagan Tribute! (Chase)
Date: Wednesday, 21 April 2010, at 7:00 a.m.
You ask how I figure the live cube takepoint so here's how I do it. Several years ago I came up with several rules of thumb for 2 and 4-cube takepoints and gammon prices in a 15-pointer. I used the Snowie MET as a guide since that IMO was the best MET at the time (this is before G11 and Kazaross/Rockwell, either of which are probably slightly better BTW). There's no huge difference at most scores between these 3 MET's, so I never bothered to adjust my rules to better fit one of the other MET's. The rules I use are simple enough to use OTB and they're pretty accurate as well. Not perfect of course but much better than just guessing.
My rules suggest that the trailer's basic 2-cube takpoint ATS is the normal 25%. The leader's 2-cube gammon price is given by the formula 68% - 3D (D is the difference in scores), so it's 56%. The trailer's 2-cube gammon price is usually around 56% as well when the leader is 7a or less. So Kit needs 25% + 56% of my net g's to take (before adjusting downward for his recube vig). I figured I had around 20% net g's so that raises Kit's 2-cube gammon-adjusted takepoint to around 36%.
How about recube vig? The formula I use for the leader's 4-cube takepoint ATS is 25% + 3D/8 so it's around 26.5%. The cube will be nearly dead if I take so there's next to no cube vig from holding the cube. If this was a normal moneylike score where you could recube to 8 like you could in a money game you could use 20% in this step rather than the 26.5% ATS.
So if Kit just takes and never recubes, he needs 36% cubeless chances to take. If he takes and always redoubles with perfect efficiency (when I have 26.5% winning chances), he can take with 73.5% of 36% which is a little less than 27% cubeless chances. The reality is usually about 70% of the way from the never redouble takepoint to the perfect efficient redouble since you very seldom can always recube when the oppt has a marginal take/pass. 70% of the way from 36% to 27% is around 29.7% which would be my guesstimate for his true takepoint. If his cubeless chances are this high, he should take. If not, he should pass.
A few other comments about this method. First of all, the 70% efficiency estimate is usually about right but certainly not always. Say you get cubed in this kind of position: You have a 20 or 21-point holding game, a winning board/prime, you're way behind in the race, virtually no gammons for either side, and the oppt has to clear an outside point 6 in front of your anchor. The cube is worth very little here. You hardly ever win the race so the chance of finding an efficient bearoff recube is close to nil. An exception might be if the oppt clears the outside point but blots on his 6 or 5 point and you hit the shot when he has 5 or so men off. You also won't be able to recube if the oppt leaves a shot while clearing the outfield point since you'll be a dog to hit. OTOH, sometimes the cube efficiency is greater than 70%. Two checkers on each 2-point or one checker on each 6-point, for example. Secondly, you might be wondering why to not factor in both player's gammon chances when calculating your 4-cube takepoint. That's a good question. I learned this method from Chuck Bower and I remember asking him this very question but I don't remember his answer (I remember it making sense at the time however). If Kit does redouble, my OTB rules for my/his 4-cube gammon prices are 20% - 2D (not to go below 6%)/ 80% (less 16% per point of overage if applicable) = 12%/80%. Third, I didn't have to go through all this math OTB since I had gone through this live cube method enough times ATS to know that if I didn't think it was a take for money, that it was good enough for the leader to offer an initial double. It looked like a pass for money, so I was sure it was a double.
My rules of thumb were pretty accurate compared to Snowie's MET:
Trailer's basic 2-cube takepoint: I used 25%, it sez 26.1%.
Trailer's/Leader's 2-cube gammon prices: I used 56%/56%, it sez 57%/53%.
Leader's basic 4-cube takepoint: I used 26.5%, it sez 27.2%.
Trailer's/Leader's 4-cube gammon prices: I used 80%/12%, it sez 77%/13%.
Snowie's MET gives the trailer slightly higher winning chances than G11 or K/R which results in the takepoints and gammon prices being a little closer to the normal 25%/50% than if you use either of these other MET's.
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