SCOREs with Different Indexes

How much do card counting indexes matter?

Here we will use the same chart as on the previous page, but we will vary the number of indexes used. Red indicates the SCORE using no indexes at all including no Insurance. Green adds the top 20 indexes. This is Don Schlesinger's Illustrious 18 and Fabulous 4 Surrender indexes minus the ten splits which few players use these days. Blue indicates the gain in SCORE using over 100 indexes. At very poor penetration on the left of the chart, we can see that the top 20 indexes perform nearly as effectively as 100+ indexes. There is almost no blue gain. At low penetration all those extra indexes just don't help. The middle of the chart displays more common penetrations. Here the top 20 indexes still provide the vast majority of the gain of 100+ indexes. At deep penetrations at the right of the chart, the picture changes. The top 20 indexes still give us the majority of gain. But now we see a substantial additional gain from additional indexes. The great range of possible counts near the end of the shoe is behind this gain.

What about single-deck?

Let us look at the same subject but with single-deck, one player and a bet spread of only 1 to 3 units. This chart is significantly different. The top 16 indexes displayed in green still provide the majority of the gain. But the additional blue indexes are substantially more important at low and medium penetrations. Peter Griffin in The Theory of Blackjack discusses the importance of playing strategy in single-deck games. Also note that the SCORE curve does not accelerate upward in single-deck as it does in six decks above. In this chart, a cut card was used. The actual number of cards dealt is higher than the number of cards before the cut card because you don't shuffle until the round ends. Because the number of rounds changes as penetration increases, the number of actual cards dealt does not have a linear relationship to the number of cards after the cut card. This causes the changes in the curve. This effect is not seen with six decks because there are far more rounds. It also does not appear in single-deck if a cut card is not used. The cut card effect will be discussed further on a later page.


Sim details

  • Six decks, S17, DAS, LS, Heads-Up, Hi-Lo, truncate, half-deck resolution, penetrations from 26-130 cards cutoff by the card, optimal betting
  • Single Decks, H17, Heads-Up, Hi-Lo, truncate, quarter-deck resolution, penetrations from 26-130 cards cutoff by the card, optimal betting
  • Three sets of indexes
  • Two billion rounds each


copyright © 2007, Norm Wattenberger, All rights reserved