How Many is That? Pot Smokers in Colorado

These two sentences appear back to back in a WaPo article on a report on marijuana usage in Colorado. Both are inaccurate out of context.

Adult residents either smoke pot (relatively) few times a month or nearly every day—there are few in the middle.

More than half of all adult resident users consume the drug in some form fewer than six times a month.

The author, Niraj Chokshi, knows, but does not say in these sentences, that only 9% of Coloradans had used marijuana, in any form, 12 times in the last year. He cites this statistic in the paragraph just above the first sentence. But as sentences are supposed to capture a complete idea, leaving out the statistic that places the idea in context is almost certain to confuse some folks.

I don’t think Chokshi means to do this. But taken out of context these sentences imply:

  1. All adult residents consume the drug a little everyday at least.
  2. More than half of all adult residents consume marijuana fewer than 1-6 times a month, the rest use more often.

In reality the relevant universe here are the set of individuals who are

  1. adult
  2. residents of Colorado
  3. and who use marijuana at least 12 times per year

So not “more than half” of our more than 5 million residents, but “more than half” of 9% of that number. Using just Choksi’s out of context sentences you might think there are millions of pot smokers in Colorado. There are, in fact, (according to the cited report’s very good methodology, btw) just under 500,000 smokers. So, the “more than half” here is talking about a couple hundred thousand smokers. That’s not nothing, but it ain’t millions either.

It’s an unforced error and it makes this issue harder to understand given the limited amount of cognitive power people can be expected to expend on any one article.

The important part of this report, btw, is that few who use smoke everyday or most days (which includes nearly all of the *medical marijuana* folks) account for nearly 70% of all the pot consumed in Colorado. Choksi doesn’t miss this point, but he does bury it a little.