Why did casino blackjack winnings drop

One issue in a court case was whether a casino's lower winnings at blackjack were consistent with historical variation. Significance tests indicated that they were not. Using explanatory variables measuring the volume of casino chips purchased, credit granted to players, player mix, and time patterns, regression analyses could not fully explain the six month dip in winnings. One proposed explanation for the dip was skimming at two particular blackjack tables. While this explanation was refuted by an analysis of extreme wins and losses by table bet maximum, a credible explanation for the winnings dip has yet to be discovered. 1. Prologue. For over six months, a large Las Vegas casino had been experiencing sharply reduced winnings at its blackjack tables. Concerned about this turn of events, management increased surveillance of the blackjack tables, changed card shuffling procedures, moved dealers from table to table more frequently and in an unpredictable way, and ultimately dismissed the blackjack 'pit boss'. Lower blackjack winnings persisted in spite of these steps. Management believed that dealer cheating was the cause of the drop in winnings, but was not able to uncover any direct evidence of such cheating. In frustration, the casino management decided to dismiss blackjack dealers whom it believed were most likely to be cheating. The drop in winnings was occurring for the day shift and the swing shift; winnings for the graveyard shift remained relatively constant during the period. Also, management believed that since more experienced dealers tend to be more skillful, a 'first in, first out' rule should be used in deciding whom to dismiss. There were about 40 replacement dealers that could be hired on short notice. Putting all these considerations together, the casino dismissed about 40 blackjack dealers who worked the day shift and the swing shift and who had the longest tenure with the casino. The dismissals all occurred on a single day. The blackjack dealers who were dismissed brought suit against the casino in Federal Court alleging age and sex discrimination. All the dismissed dealers were men over forty while the replacement dealers were predominantly younger women. Attorneys defending the casino in the suit considered arguing, among other things, that there was a 'compelling business