Editing Card counting (section)

=== Technology for detecting card counters ===
Several semi-automated systems have been designed to aid the detection of card counters. The [[MindPlay]] system (now discontinued) scanned card values as the cards were dealt. The [[Shuffle Master]] Intelligent Shoe system also scans card values as cards exit the shoe. Software called Bloodhound and Protec 21<ref>{{cite web |title=Digitace Website |url=http://www.digitace.com |access-date=20 March 2009 |publisher=digitace.com |archive-date=15 January 2009 |archive-url=https://web.archive.org/web/20090115004810/http://www.digitace.com/ |url-status=live }}</ref> allows voice input of card and bet values, in an attempt to determine the player edge. A more recent innovation is the use of [[RFID]] signatures embedded within the casino chips so that the table can automatically track bet amounts.<ref>{{cite web |last=Gilbert |first=Alorie |title=CNET News story, "Vegas Casino Bets on RFID" |url=https://www.cnet.com/tech/services-and-software/vegas-casino-bets-on-rfid/ |access-date=20 March 2009 |publisher=News.com.com |archive-date=26 August 2021 |archive-url=https://web.archive.org/web/20210826230340/https://www.cnet.com/tech/services-and-software/vegas-casino-bets-on-rfid/ |url-status=live }}</ref>

Automated card-reading technology has known abuse potential in that it can be used to simplify the practice of ''preferential shuffling –'' having the dealer reshuffle the cards whenever the odds favor the players. To comply with licensing regulations, some blackjack protection systems have been designed to delay access to real-time data on the remaining cards in the shoe.<ref>{{cite web |title=High-Tech Casino Advantage Play: Legislative Approaches to the Threat of Predictive Devices |url=https://core.ac.uk/download/pdf/10678382.pdf |access-date=19 November 2017 |website=Core |archive-date=8 November 2017 |archive-url=https://web.archive.org/web/20171108080515/https://core.ac.uk/download/pdf/10678382.pdf |url-status=live }}</ref> Other vendors consider real-time notification to surveillance that a shoe is "hot" to be an important product feature.<ref>Aventura Technologies, [http://www.ati247.com/pdf/Real-Time%20Casino%20Solution_v01.2.pdf Real Time Casino Solution (PDF)] {{Webarchive|url=https://web.archive.org/web/20070306161251/http://www.ati247.com/pdf/Real-Time%20Casino%20Solution_v01.2.pdf |date=2007-03-06 }}, diagram 12, "Advantaged Play Server"</ref>

With card values, play decisions, and bet decisions conveniently accessible, the casino can analyze bet variation, play accuracy, and play variation.

''Bet variation''. The simplest way a card counter makes money is to bet more when they have an edge. While playing back the tapes of a recent session of play, the software can generate a scatter plot of the amount bet versus the count at the time the bet was made and find the trendline that best fits the scattered points. If the player is not counting cards, there will be no trend; their bet variation and the count variation will not consistently correlate. If the player is counting and varying bets according to the count, there will be a trend whose slope reflects the player's average edge from this technique.<ref>Arnold Snyder's ''[[Blackjack Forum]]'' periodical featured a printout that demonstrated this feature</ref>

''Play variation''. When card counters vary from basic strategy, they do so in response to the count, to gain an additional edge. The software can verify whether there is a pattern to play variation. Of particular interest is whether the player sometimes (when the count is positive) takes insurance and stands on 16 versus a dealer 10, but plays differently when the count is negative.