True Count Calculation for Various Editions of Professional Blackjack

**Gronbog** · 01-04-2019, 09:32 AM

I know I've seen the answer to this here at some point, but I can't seem to find it.

Wong changed the way he calculated the true count from one edition of Professional Blackjack to another from rounding to truncating etc..

Does anyone know what method was used to compute the indices in the 1994 edition? I'm hoping that the answer is flooring. If the answer is truncating, then that would be ok as well, since I can then derive the flooring indices by decrementing the negative indices.

**Freightman** · 01-04-2019, 09:58 AM

Originally Posted by Gronbog

I know I've seen the answer to this here at some point, but I can't seem to find it.

Wong changed the way he calculated the true count from one edition of Professional Blackjack to another from rounding to truncating etc..

Does anyone know what method was used to compute the indices in the 1994 edition? I'm hoping that the answer is flooring. If the answer is truncating, then that would be ok as well, since I can then derive the flooring indices by decrementing the negative indices.

I’m not home right now, but Im pretty sure that the 1994 edition was truncated. Easy enough simply by checking various indices from the tables startiing from around page 253. Several common indices should be off by “1” versus flooring indices.

**Gronbog** · 01-04-2019, 10:13 AM

It may not help for you to arrive home. I have the book but the method used does not appear to be explicitly stated.

**Freightman** · 01-04-2019, 10:24 AM

Originally Posted by Gronbog

It may not help for you to arrive home. I have the book but the method used does not appear to be explicitly stated.

It’s not stated. Comments derived from indices being different than other published flooring indices. It’s “inferred”.

**Midwest Player** · 01-04-2019, 11:08 AM

From the latest kindle edition of Professional Blackjack regarding tables in back of book.

"These tables differ from earlier editions of this book. The change was increasing all the negative numbers by 1 because in the 1981 and earlier editions of Professional Blackjack, strategy numbers were presented using a different assumption as to how to round count per deck."

Wong, Stanford. Professional Blackjack (Kindle Locations 4962-4964). PiYee Press. Kindle Edition.

**Three** · 01-04-2019, 11:11 AM

Truncated.

https://www.qfit.com/CalculatingTrueCounts.htm

**Gronbog** · 01-04-2019, 11:16 AM

Thanks Three. From the referenced page:

"Truncate – For positive numbers, round down and for negative numbers round up. This is the method used in the 1994 and later editions of Professional Blackjack. 1.5 is rounded down to 1. -1.5 is rounded up to -1."

**Three** · 01-04-2019, 11:25 AM

More than happy to help anyway I can at any time.

**DSchles** · 01-04-2019, 07:00 PM

Originally Posted by Gronbog

Thanks Three. From the referenced page:

"Truncate – For positive numbers, round down and for negative numbers round up. This is the method used in the 1994 and later editions of Professional Blackjack. 1.5 is rounded down to 1. -1.5 is rounded up to -1."

Surprised no one here recalls the revolution when Wong changed all his negative indices. It caused a terrible upheaval among players, and I personally exhorted him not to do it. In any event, yes they are now forever truncated, which is surely not the best way to go.

Don

**dharmaprija** · 01-05-2019, 01:15 PM

Flooring is the most risk averse correct D.S.?
When practicing with Casino Verite and in real life it's what I do but I defer to your expertise Don.

**Ole** · 01-28-2019, 06:09 AM

In a discussion on another thread about Index Variations back in November I mentioned that, *"When quoting any Index numbers, one must consider the source and the specific author's process at the time." This is not only to address Flooring versus Truncating, but also how you actually treat that decision threshold with your actions. That was one thing not adequately covered in the otherwise excellent website that Three provided.*

Action to take at a given Index:

Many authors, Don included, say to take your indicated action (Stand, Double, Split, Surrender, Insure) "at the index number and above" such as Stand >=2 (e.g. 12 vs. 3 in 6D S17), and Stand >= --1 (for 12 vs. 6), so one would only Hit less than an index number.

But some people will flip how they use the negative indices by changing the action itself around, and would say to take an Action "at or above" a positive index,* but Hit "at or below" the negative index.* Such as Stand >=2 (12v3), but Hit <= --2 (12v6).

So you really need to buy the book or otherwise really learn where the person is coming from when they say "the index is --1."

Ole

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**Dog Hand** · 01-28-2019, 08:15 AM

Ole,

Did you mean 16 versus 10 in your examples? The index for 16 versus 6 is certainly much lower than -1.

Dog Hand

**Three** · 01-28-2019, 11:04 AM

I don't like to worry about BS. I have and index for a decision. If it is a hit/stand decision you stand at or above the index. It just adds an extra step and a possible cause for confusion to think what BS strategy is and then the index and then decided whether you hit or stand at the index by what BS says to do. But at the index the gain is almost nothing so you could do it either way without much cost.