Way down the page, Mister M asked me about the practicalities of applying the NRS formula in real-life play. I gave my two cents worth down there. In BBIBJ, Arnold Snyder provides some excellent practical advice on the matter. Snyder considers a shoe in which the first deck has an estimated running count of -7 and an expected edge of 3% (the segment comprising a big-card slug and an unknown component). Accordingly, the plan is to use a betting and playing strategy that is appropriate to the situation. Here is part of what Snyder writes:
"Note, and this is important: I will commit to playing this strategy throughout the entire one-deck segment. I will start my running count at 0, as always, but I will remember that it is always estimated at +7 higher as it goes up and down through the segment. However, if my running count goes down to -8 on the first round, I will NOT assume that my true edge of 3 percent has disappeared. It is, in fact, far more likely that the unknown segment that was married to my segment also contained excess high cards than it is that all the excess high cards in my segment clumped into the first round of play.
"As you go through the segment, you may slowly cut back on your bet if many excess high cards, over and above what your slug contained, continue to come out. And perhaps on the last round of the segment, cut back to a small bet. But the easy rule to remember is to just bet and play that sucker from the top to bottom like you've got a 3 percent edge! Believe me, you will play your slugs far more accurately, and make lots more money with this approach, than if you drop your bet as soon as your 'estimated' running count goes back down to 0." (BBIBJ, p.169)
This passage is beautiful in its apparent simplicity. In actuality, it is more sophisticated than might at first seem obvious to the uninitiated, and informed by the central implication of the NRS formula. Snyder is explicitly taking account of the fact that a dramatic drop in the running count might be due to the cards from our slug being dealt, but equally, it might be because the unknown portion is also rich in big cards. In other words, Snyder's method of approach is highly practical, yet broadly consistent with the NRS formula.
It should be stressed that this approximate method is made acceptable by the fact that Snyder recommends in an earlier passage estimating the segment count conservatively. In the above example, the segment count estimate started at -10, then got revised down to account for the portion of unknown cards, and to allow for errors due to dealer inconsistencies, player errors, etc. As Snyder puts it:
"It is more profitable, and accurate, to estimate your edge conservatively, but then to play the slug with aggression."
I think this passage from Snyder is the best practical advice I've seen on issues surrounding the NRS formula. It should go without saying that the book itself, and his three-part BJ Forum series (if it is still available), are 'must haves' for the aspiring tracker.
"Note, and this is important: I will commit to playing this strategy throughout the entire one-deck segment. I will start my running count at 0, as always, but I will remember that it is always estimated at +7 higher as it goes up and down through the segment. However, if my running count goes down to -8 on the first round, I will NOT assume that my true edge of 3 percent has disappeared. It is, in fact, far more likely that the unknown segment that was married to my segment also contained excess high cards than it is that all the excess high cards in my segment clumped into the first round of play.
"As you go through the segment, you may slowly cut back on your bet if many excess high cards, over and above what your slug contained, continue to come out. And perhaps on the last round of the segment, cut back to a small bet. But the easy rule to remember is to just bet and play that sucker from the top to bottom like you've got a 3 percent edge! Believe me, you will play your slugs far more accurately, and make lots more money with this approach, than if you drop your bet as soon as your 'estimated' running count goes back down to 0." (BBIBJ, p.169)
This passage is beautiful in its apparent simplicity. In actuality, it is more sophisticated than might at first seem obvious to the uninitiated, and informed by the central implication of the NRS formula. Snyder is explicitly taking account of the fact that a dramatic drop in the running count might be due to the cards from our slug being dealt, but equally, it might be because the unknown portion is also rich in big cards. In other words, Snyder's method of approach is highly practical, yet broadly consistent with the NRS formula.
It should be stressed that this approximate method is made acceptable by the fact that Snyder recommends in an earlier passage estimating the segment count conservatively. In the above example, the segment count estimate started at -10, then got revised down to account for the portion of unknown cards, and to allow for errors due to dealer inconsistencies, player errors, etc. As Snyder puts it:
"It is more profitable, and accurate, to estimate your edge conservatively, but then to play the slug with aggression."
I think this passage from Snyder is the best practical advice I've seen on issues surrounding the NRS formula. It should go without saying that the book itself, and his three-part BJ Forum series (if it is still available), are 'must haves' for the aspiring tracker.