Large casinos in Nevada are continuing their losing streak, reporting more than a billion dollars in losses for the most recent fiscal year. Here, a view of Paris Las Vegas, a hotel and casino located on the Las Vegas Strip. John Gurzinski/AFP/Getty Images hide caption

itoggle caption John Gurzinski/AFP/Getty Images

How do you turn a casino into an economics lab? Get everybody to use a loyalty card, and start running controlled experiments. Jae C. Hong/AP hide caption

itoggle caption Jae C. Hong/AP