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Sunday, July 27, 2014

Polling Problems re Marijuana Legalization

Today's New York Times has an editorial -- by the editorial board -- in favor of legalizing marijuana; i.e. ending the 40-year federal ban on it, although continuing to prohibit sales to kids under 21.  All of the comments agree; tobacco and alcohol are clearly worse for you, and the costs of "fighting" the law against marijuana are enormous.  Not just the financial costs of catching people, trying them, and in many cases throwing them in jail, but also the social costs of ruining lives (disproportionately those of young black men) by criminalizing this kind of conduct, which, after all, is widely accepted socially.

Reading that motivated me to see how we are doing here in Virginia, and that led me to this article. It turns out the vast majority of Virginians support legalization for medical use, but it's a close call for legalization generally.  What's interesting to me is that they say that people 65 and older are 2-1 against legalization.  I could be wrong, but it sounds like they were pretty stupid in dividing up the "age groups" in the poll.  Presumably they have pre-designed polls where they record age groups, and one of the categories is simply 65 and older.  In general, that's a pretty logical category -- 65 is an important age re retirement, medicare eligibity, etc., so in general it's a good dividing line --, but for marijuana use, it's almost certainly really stupid, and it probably masks some interesting information.

Why do I say that?  Think about it -- people who are 65 today (in 2014) were born in 1949 or 1948, and thus came of age in the 1960s, and were at high risk of becoming hippies and potheads.  Many of them still smoke pot today.  For reference, Paul McCartney was born in 1942, John Lennon in 1940, and Mick Jagger in 1943.  The summer of love was 1967, when someone born in 1949 was 18.  These people were only 20 in 1969, when Woodstock happened.  In other words, 65 is a pretty dumb dividing line when it comes to dividing young from old in the pot legalization debate.  I have no doubt that people who came of age in the 50s -- people born e.g. a decade earlier; in the late 1930s -- would today be against marijuana.  By the time of Woodstock, they all had families and jobs and had basically missed the marijuana boat.  And there are a lot of them out there.

[Here's an aside that I need to remember to ask next time I'm talking to someone about the science of polling.  I personally never have time for polls, and I would guess there are many other busy people like me who just don't take them.  But older people have more time, and also probably feel strongly about certain issues and want their views to be heard.  So my guess is that the age distribution of poll-respondents differs greatly from the distribution of the normal population.  Am I right?  And if I am, do polls correct for this?  It's not enough to simply report the overall result and then say, as the Virginia poll does, that a majority of young people favor legalization, while 2/3 of old people are against it.  That doesn't tell me if there has been a correction for age distribution in reporting the overall result.  In other words, one can imagine two worlds in the science of polling:   (1) the poll simply interviews 1000 people, notes their ages, but then does no correction, and (2) the poll somehow does a correction.  If 500 of those people are 65 and older, and they think differently on the polled issue than the rest of the population, you will get a highly misleading result absent a correction.  One can imagine a number of different ways to try to correct for this.  I.e. one would get the overall votes for each age group, and then "weight" the age group's contribution based on the true age distribution in the population.  I.e. even if a disproportionate number of old people respond to your poll, you take their response as representative of "old people" generally, and do the same for each age group.  Then you use what we know about the percentage of "old people" and other age groups in the country to guess what the true distribution is.  This then raises questions about how to ensure that the results in any given age group are accurate -- i.e. you need to poll above a certain number.  And then that presumably introduces a separate potential error for each age group.  I would guess that the "science of polling" has answers to these questions, but then again, most polls are so unreliable that maybe they just don't.]

Back to the marijuana poll.  Given the almost certain difference in views between people aged 65-70 or maybe 75, and those 75 and older, it seems to me the poll almost certainly should have divided up the age groups differently.  In fact, it's possible that those aged 65-70 would feel more strongly about legalizing pot than any other age group.  And yet they were simply averaged in to the older age group, which consists of many people who never even had the opportunity to try pot.

It's interesting also that the vote in Virginia was 84% in favor of legalizing medical marijuana.  One can readily see how all the anti-pothead prejudices of the 50's generation fell away with that question -- if there's a chance that they themselves would get to use it legally, and it might help them medically, then of course it should be legal for that purpose.

One thing that this tells us is that the anti-marijuana sentiment will die out soon enough.  I.e. really, it's only people currently over 75 or 80 that are strongly against legalization to begin with, and the ranks of those people are getting thinner every year.  These people are mostly out of touch on the marijuana issue, and are dying out anyway, but because they vote strongly against it, polls make it look like a close call here in Virginia.  Really, it isn't.  But politicians don't care -- they need to keep currying favor with this bloc.

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