Wagering on a large scale: Relationships between public gambling and game manipulations in two state lotteries.

Public wagering was examined in relation to game adjustments during the first 523 draws of Oregon's "Megabucks" lottery and the first 540 draws of Arizona's "The Pick" lottery. Oregon's lottery was modified five times during this period, and Arizona's lottery underwent four modifications. Public wagering was not related to decreases in the odds of winning in either state. Wagering increased in both states following the introduction of a minimum $1 million jackpot. Wagering also increased following a change in game frequency from weekly to semiweekly draws. Sales trends in both states suggest that over the period examined, larger jackpots were required to maintain previous levels of lottery play. These data suggest that public participation in gambling can be manipulated by state lottery commissions through adjustments in lottery contingencies.