As we've reported, Amendment 64, the Regulate Marijuana Like Alcohol Act, had a 53 percent to 43 percent lead in a recent Public Policy Polling survey. But by another measure -- predictions from the online trading exchange Intrade -- the measure is doing even better. At this writing, it's being given a 68 percent chance of passage.

How does Intrade work? "The website's members bet on the outcomes of non-sports-related future events," note our friends at Wikipedia -- a concept that blends the stock exchange with a sports book.

Here's the latest Amendment 64 entry:

These numbers have been on the rise of late. Here's a chart showing Amendment 64's Intrade performance over time: The shift has been especially dramatic of late. Yesterday, for instance, Amendment 64 was given a 62 percent chance of victory -- meaning there's been an approximate 6 percent leap in 24 hours. And the marijuana proposal in Washington state is on a similar trajectory. Yesterday, it registered a 73 percent ranking. Today, it's at 75 percent.

Are these numbers anything more than curiosities? Perhaps, as witnessed by the Intrade numbers for Proposition 19, a 2010 marijuana proposal in California. Ballotpedia features a chart showing declining support for the measure over the month before the election:

In the end, Proposition 19 lost handily.

By the way, the presidential race appears to be a dead heat right now -- but Intrade currently gives Barack Obama a 67.3 percent chance of reelection, as compared to Mitt Romney's 33.1 percent. Will any of these predictions prove accurate? We only have a few days until we'll find out.

More from our Marijuana archive: "Marijuana: Amendment 64 opponents lying, intimidating supporters, says Mason Tvert."