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Best of Alan Krigman

Gaming Guru

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Playing It Smart: Playing multiple spots at blackjack

24 August 2009

Some blackjack buffs enjoy playing multiple spots simultaneously. Few have more than intuition and specious logic about their preference. Mostly, their explanations have to do with things like "you get more action," "you make more on hot shoes," "wins on one side can offset losses on the other when the game is cold," or "you change the flow of the cards, which may turn a losing shoe into a winner." Card counters have other reasons, principally involving getting a greater share of the good cards and increasing total wagers under favorable conditions.

From the standpoint of edge, on a round-by-round basis, one spot at $10 is the same as two spots at $5 each. Pretend a player follows good Basic Strategy with the usual rules. Edge is 0.5 percent so the house averages $0.05 per round either way.

When time enters the picture, the impact of edge differs in the two cases. This, because rounds per hour decrease as more spots are executed. Say, for instance, three solid citizens are at a table. If each bets on a single spot, roughly 100 rounds will be dealt per hour. That's 300 hands apiece in three hours. At 0.5 percent of $10, these players will each donate $15 to the casino mortgage fund. Were one of those folks to bet on two spots, the decision rate would fall to about 80 rounds per hour 240 in three hours. The theoretical loss due to edge for the person on the two spots, assuming $5 each, would still be $0.05 per round but would drop to 240 x 0.005 x 2 x $5 or $12 for the session.

In the statistically short span of a session or casino visit, bettors essentially don't notice losses due to edge. They're far more strongly influenced by the bankroll swings induced by volatility. In this regard, the impact of single or multiple hands differs round-by-round as well as during a session.

Spreading the same total across several hands reduces swings. The characteristic bankroll change (precisely, "standard deviation") is $11.30 for a single $10 hand and $9.42 for two $5 hands at the same table. Over the 300 rounds the bettor on a single spot under the cited conditions would typically get in three hours, a normal bankroll up- or down-swing might be about $195. For the 240 rounds played on two spots, it would be approximately $145.

One implication of the difference in volatility is that chances of remaining in action for a given time duration improves markedly on any given bankroll by distributing a wager across several hands, as opposed to risking it all on a single spot. As an example, the chance of surviving for three hours on a $250 stake, with $10 on one spot, is 78 percent. Splitting the $10 evenly across two spots raises this to 90 percent.

Another consequence of playing multiple spots is that the likelihood of earning a desired profit before going belly-up on any stake decreases slightly when a given total gets spread out. The chance of doubling before losing $250 with $10 on one spot is 45 percent; it's 43 percent with $5 on each of two spots.

Here's an alternate way of viewing these phenomena. Spreading allows the total at risk to be raised modestly without seriously affecting the chance of lasting for a desired session period or of reaching a profit target before biting the dust.

Going from $10 on one spot to $7 on each of two, the chance of survival decreases only from 78 to 75 percent. The same change barely reduces the chance of doubling before losing a $250 bankroll the decline is a mere quarter of a percentage point.

The good news is that the choice of playing one or multiple spots in various ways gives blackjack aficionados the opportunity to decide which they consider more important: the chance of getting their money's worth of action during a casino visit, or of reaching some profit target before busting out. They bad news is they can't have it both ways. The beloved bard, Sumner A Ingmark, cleverly captured this conundrum in his cogent couplet:

Aggressive bettors make big bucks, but well may bust out trying,
Their prudent counterparts earn less, yet less oft end up crying.

Alan Krigman

Alan Krigman was a weekly syndicated newspaper gaming columnist and Editor & Publisher of Winning Ways, a monthly newsletter for casino aficionados. His columns focused on gambling probability and statistics. He passed away in October, 2013.
Alan Krigman
Alan Krigman was a weekly syndicated newspaper gaming columnist and Editor & Publisher of Winning Ways, a monthly newsletter for casino aficionados. His columns focused on gambling probability and statistics. He passed away in October, 2013.