There's no better way to spend the first Saturday in May than watching the Kentucky Derby in person below the spires at Churchill Downs. Still, a party in the neighbor's backyard is not a bad way to spend Derby day. But, the hoopla can be a bummer for NBC. When everyone gathers around the TV set, the network gets a lot of out-of-home (OOH) viewers not counted in the Nielsen ratings. Arbitron, however, has data that seeks to capture it and shows NBC gained a 34% lift by one metric from OOH numbers for the Derby.