I just read your response regarding the question about the 3% variance checks and I felt that your answer missed the mark. Variance checks are something I also do on a monthly basis at my casino. What the writer is referring to is the NIGC (National Indian Gaming Commission) MICS (Minimum Internal Control Standards).
The section of the MICS entitled Standards for Evaluating Theoretical and Actual Hold Percentages has a sub-section that reads: "(18.) For those machines that have experienced at least 100,000 wagering transactions, large variances (3%) between theoretical hold and actual hold shall be investigated and resolved by a department independent of the gaming machine department with the findings documented and provided to the Tribal gaming regulatory authority upon request in a timely manner."
The department "... independent of the gaming machine department ..." is normally the Revenue Audit or Accounting department. Part of this is process is to have the Slot Maintenance department first review the games on the variance list to determine if there are any mechanical or configuration problems. If there are any problems found, then they are resolved and this information is reported back to Revenue Audit.
While I agree that 100,000 spins, or games played, is too small of a sample to expect a game to approach its stated hold percentage, it is a point at which a game could be checked for problems. Let's say, for example, that a game is supposed to be configured for a 95% payout but was incorrectly set for a 93% payout.
Now let's say that after 100,000 spins, the game's actual payout is 91%. While it's paying only 2% lower than how it is set, it is 4% lower than what it was supposed to be set at. An inspection of this game's actual configuration will show that it is incorrectly set. It can now be correctly configured to 95% and this will be reported to Revenue Audit.
Contrary to what many people think, each game's software normally has multiple payout percentages available for selection during configuration. A slot technician who is not paying attention can accidentally select the wrong payout percentage. That's why these variance reports are required by MICS. They are intended to protect both the players and the casino from human error.
This is part of the system of checks and balances that helps to ensure casinos are running fair games for the gaming public.
The Slot Guru
Thanks for providing an insider's view of checking slot machine performance.