Estimation of True Count Using the Red 7:

Sensitivity of Blackjack True Count to Errors in Estimating Decks Remaining

by Conrad Membrino
© Blackjack Forum 1990

rc.r7 = red 7 running count
n = number of decks
tc = true count
dr = decks remaining

rc.r7 = 2*n + (tc – 2) * dr

Number of Decks = 8

Red-7 Running Counts corresponding to various True Counts for an Eight deck game

Eight Deck Game	rc.r7
rc.r7 = 23456 + (7p/2) – TAp	decks played
tc	rc.r7	3	4	5	6	7
2	16	16	16	16	16	16
3	16 + dr	21	20	19	18	17
4	16 + 2*dr	26	24	22	20	18

Estimation of true count with the Red 7 in an Eight Deck Game:

1. Estimate decks remaining
2. Compare Red 7 running count with 16, 16 + dr, or 16 + 2*dr for true counts of 2, 3, or 4
3. Use calculated true count with High-Low strategy indicies.

Sensitivity of True Count to Errors in Estimating Decks Remaining:

1. The Closer to the Pivot Point, the less sensitive the true count is to errors in estimating the decks remaining.
2. At the pivot point, ther true count is independent of the decks remaining
3. Pivot Point of the Red 7: True Count = 2
4. Pivot Point of High-Low: True Count = 0
5. At True Counts = 2:
   (a) Red 7 is closer to its pivot point (tc=2) than the High-Low is to its pivot point (tc=0)
   (b) Red 7 is less sensitive to errors in estimating decks remaining when calculating true count.
   (c) Red 7 gives more accurate true counts than High-Low.

Example:

A = Actual
E = Estimated
dr:a = actual dr
dr:e = estimated dr
tc:a = actual tc
tc:e = estimated tc

Eight Decks

r7 = red 7	hi = high-low
tc.r7 = 2 + (rc.r7 – 16) / dr	tc.hl = rc.hl / dr

Eight Decks
dr:a = 4 and tc:a = 3

		Red 7			High-Low
		estimated	error		estimated	error
dr:e	rc.r7	tc:e	(tc:e – tc:a)	rc.hl	tc:e	(tc:e – tc:a)
6	20	2.7	-0.3	12	2.0	-1.0
5		2.8	-0.2		2.4	-0.6
4		3.0	0.0		3.0	0.0
3		3.3	0.3		4.0	1.0
2		4.0	1.0		6.0	3.0