You're incorrect about the methodological flaws.

Only 50-year-olds are mentioned because this is a longitudinal cohort they've been testing since 1977, and this year (2009) it's their turn to be reported.

The "adjusted" number is higher than the measured number because some people answered the survey ten years ago saying they'd tried marijuana in the past year but then in the current survey the same respondent said "no" when asked if they'd ever tried marijuana in their lifetime. So they're publishing both the actual numbers and the "we know you're probably lying" numbers.

"What does that mean adjusted?"

It's explained the study.

"About this time is where I say a study has too many methodological flaws and should be disregarded."

Try actually reading it. It's really not that difficult to understand. The 'maturity recanting effect' section here also gives a brief summary of what they did and why:

http://www.erowid.org/psychoactives/statistics/statistics_ar...

Don't criticize studies without taking the time to understand them, otherwise you just sound like these people:

http://www.youtube.com/watch?v=RjX1IaU1A0w

I feel very comfortable stating with 100% certainty that your claim that the study said 85% of all people report being marijuana users (exact words: "around 85% of Americans use marijuana alone") was completely and outrageously inaccurate. It's humorous but a touch sad that you can't admit you were completely and utterly wrong. Lay off the stuff, clear your head, and re-read the report, dude.

It's also charming that you cite erowid.org as a reliable unbiased source. I am familiar with the site and have read it. It is a radical pro-drug site.

Where did he call them unbiased? (I would call them reliable, though they certainly have an agenda. But they've always struck me as working hard to present facts, or at least label opinion as such. Certainly I can't think of another site about drugs that I would trust over Erowid. And I would be very interested indeed to hear of deliberately misleading information posted there.)

I think Erowid is about as unbiased as it gets. All they do is provide information about drugs, they are neither advocating drug use nor condemning it.

Even their legal articles don't take any position on what drug policy should be, all they do is explain the case law that exists.