In California, Proposition 19 will appear on the ballot in November, allowing voters to vote on the legalization of marijuana.

The problem is that recent polling on the issue show different results. A recent PPP poll showed a 16 point lead as well as a Survey USA poll that showed a 10 point lead. Other polls such as a Field Poll that showed a 4 point disadvantage and a Reuters/Ipsos poll showed a 2 point support deficit.

Nate Silver at FiveThirtyEight.com writes that polls that use an automated system return with more support for pot legalization while polls conducted by humans tend to get less support. He suggests that in automated polls, support from minority groups is noticeably higher, possibly due to a higher comfort level with automated polling.

“It’s possible that we’re seeing some sort of Bradley effect in reverse, which I’ve reluctantly dubbed the “Broadus Effect” after the given name of the rapper Snoop Dogg, himself a frequent consumer of cannabinoid-rich products.” Silver concludes. “The original Bradley Effect, named for former Los Angeles mayor Tom Bradley, occurs when respondents in surveys are asked about socially desirable behaviors, such as being free from racial prejudice. Although the racial version of Bradley effect itself is probably a thing of the past, social desirability bias may manifest itself in other ways. ”

Read his full analysis here: