The Top Pickers vs. the Pack

Justin Wolfers, a business professor at the University of Pennsylvania's Wharton School, said collective wisdom -- reflected for instance in the stock prices set jointly by millions of knowledgeable investors in the open market, and in sports betting lines determined by large groups of avid gamblers -- is more likely to be accurate than Web sites claiming to feature experts. Someone must have a track record stretching back decades before it is statistically possible to conclude whether success results from talent or random chance, he said.

"Folks who look like experts today are very likely to be lucky," Wolfers said. "If they're conditioning it only on past history, it's likely to be a lost cause."

Jessiman said he tries to rule out flukes at PicksPal by requiring that his experts play actively in three of the most recent five weeks.

At Marketocracy, Taguchi said the site tries to limit the role of luck by selecting the best investors based on factors including overall performance, percentage of accurate picks, the speed at which they cut off losers and the markets and sectors in which they are active.

Even if sites are able to identify expertise, several business professors questioned why experts would donate their wisdom to the Web rather than striking out on their own to make money.

"If they're really consistent, it's kind of hard to see how the sites will survive. The experts will leave," said Robin Hanson, an economics professor at George Mason University.

But Acevedo said he has no plans of abandoning his place at the front of a classroom and heading to Las Vegas. He said he has never gambled on sports with real money except for several visits to the racetrack.

"If I caved in and started making real bets or looked for a bookie, I'm afraid I'd go downhill right away," he said. "I'd be thinking about the money instead of going with what I feel."