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On a talkshow this morning during a discussion of the validity of random drug tests a member of the Illinois State Police stated that 70% of admitted Marijuana users also admit to using while at work. I am not finding any studies or statistics that back this up or refute it.

The claim was used to support the requirement that teachers be subject to random drug testing. That claims of what is done at home stays home is most often not true. I had not originally included this part as my skepticism is about the usage at work not about the effectiveness of drug testing.

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    @Sklivvz - Is there some reason it should be? I do not have anything against it if it really matters. – Chad Aug 18 '11 at 14:11
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    @Sklivvz - I do not know that I agree with that. But I have updated it to include the US tag. Though that may be an interesting stat to see, the percentage of people who use Pot at work in countries where it is legal/not legal. It would also be interesting to see the number of selfidentifiers vs actual users. – Chad Aug 18 '11 at 18:21
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    does musician count as an occupation? If so.... – Monkey Tuesday Aug 18 '11 at 19:06
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    Admitting to "having used while at work" is a little different than "(routinely) using at work". It seems plausible that 70% of pot smokers may have used at work some time in their life--like while they were in high school, and worked at McDonald's, but may not use at work now that they're 30-something and have a real job. – Flimzy Aug 20 '11 at 4:25
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    A thorough definition of "admitted Marijuana users" from the police may help. The sample the police have the potential to survey is going to be significantly different from a survey of the general population. There's fair chance "admitted Marijuana users" refers to those who admit it to the police when they're busted for something. Either way, there are issues of selection and perception bias, and I think the talk show is using an argument to authority to attempt to make a political point. – Joisey Mike Aug 23 '11 at 15:57
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While this doesn't prove that the hypothesis "70% of marijuana users also use while working" is false, it certainly makes it look unlikely.

http://www.icpsr.umich.edu/quicktables/quicksetoptions.do?reportKey=23782-0001_du%3A7

Using data from this site, I was able to come up with the following table. This represents employed (both full-time and part time) people who say they have ever used marijuana, and how frequently they have used over the last 12 months:

77.2% have not used at all in the last 12 months
6.5% have used 1-5 days in the last 12 months
1.5% have used 6-10 days in the last 12 months
2.7% have used 11-25 days in the last 12 months
3.6% have used 26-100 days in the last 12 months
8.4% have used 100+ days in the last 12 months

If we only consider the "recent" users (excluding the 77.2% who have not used in the last 12 months), we are left with:

28.5% have used 1-5 days in the last 12 months
6.7% have used 6-10 days in the last 12 months
12.0% have used 11-25 days in the last 12 months
16.0% have used 26-100 days in the last 12 months
36.8% have used 100+ days in the last 12 months

If this data is accurate, for 70% of current marijuana users to smoke at work, then even a good portion of even the most casual users would have to smoke at work, and that just seems unlikely. I suspect the most casual users are the least likely to smoke at work.

So I would argue that for any useful meaning of statistics, it is clear that 70% of pot users do not use while at work.

Of course, by massaging the numbers sufficiently, it may be possible to claim that 70% of people who have used at any time in their life, used at work at some time in their life--or more likely were high at work (used immediately before arriving to work, or over their lunch break, etc). But using such a statistic for anything other than curiosity, I would consider unethical, considering that 77% of "some time in their life" users no longer use at all, according to this data.

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    Good answer. In other news: 100% of potheads that smoke 20 joints per day, also smoke at work... :-) – Sklivvz Aug 22 '11 at 14:55
  • Regardless of the fact that this can't discredit the original claim, these are certainly much more 'telling' statistics - and if anything point out just how weak and meaningless the original claim is. Besides, "the Illinois State Police" isn't exactly a reputable statistics office. – Alain Aug 23 '11 at 13:29
  • @Flimzy - I do not know that you can draw those conclusions from the data here. Its possible that all of the use by those doing it 1-5 times happened while at work or went to work while still high. While I agree that only those that have been active in recent times really matter as far as this goes. So having smoked at work one time when you were young is different from smoking now. I fall into that I did when i was young catagory. But I am certian that if I still smoked now I would probably smoke at lunch... sure would make the afternoons better :p – Chad Aug 23 '11 at 13:49
  • @Sklivvz: Wait, how many of those 20-joint-per-day potheads work? – Oddthinking Nov 7 '11 at 0:55
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    @Sklivvz, doesn't your original quote assume 100% IN work? – Oddthinking Nov 7 '11 at 8:29
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For the total user population, 70% cannot have used marijuana in the workplace. I derived from table 2.11 on this paper to find that 33.6% of marijuana users aren't even employed. So if 33.6% aren't employed it can't be true that 70% are using at work.

33.6% is reached by using the 2009 data on millions of users (NOT the rate of use in past month chart) graph here. Unemployed + Other + Full Time + Part Time/ Unemployed + Other. The other column is people who are not in the workforce, but not unemployed.

(9.2+3.6+2.5+4.0)/(2.5+4.0) = .336

Table of users

However, the actual claim in the show could still have been true. The likelyhood is that the officer was just quoting a study. Since the vast majority of studies use "admission" to mean admittance to a medical facility (which is the standard definition used in medical research) and not admitting to use, then 70% could easily be an accurate number. People who are admitted to a medical facility for abuse are going to be centered towards the most severe and frequent users and would not represent the general population. Indeed, almost 30% of admitted users were referred by their employer, so the number of admitted users that use at work could realistically be within 70% (no this doesn't show it, but it does show that 70% isn't a wild crazy made up number).

  • That 33% are not always unemployed. And the figures actually show its around 20% not 33%. And looking at your reference it appear about 7% of the adult population use marijuana. So only 5-6% would need to use it for the claim to be valid. – Chad Aug 23 '11 at 20:25
  • @Chad -- No, the CDC clearly has MUCH more than 7% of the adult population using marijuana. You're looking at percent used during the past month which is a different number than total % of users (who may only use a couple of times a year). The figures show 33%. If you can get 20% show your math. – Russell Steen Aug 23 '11 at 20:27
  • The other column does not count as unemployed just because they do not have conventional jobs. So it is actually less than 20% closer to 13% – Chad Aug 23 '11 at 20:31
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    @Chad -- Did you even click through and read? From the paper: The Other Employment category includes retired persons, disabled persons, homemakers, students, or other persons not in the labor force. What part of "persons not in the labor force" is unclear? It's standard to leave the groups mentioned there as something other than Unemployed, because unemployed is generally used to mean "looking for work, but not getting it". – Russell Steen Aug 23 '11 at 20:35
  • I disagree but its irrellevant. Just because it is unlikely that 20% of the total workforce has used pot at work in the last year does not mean that it is not happening. – Chad Aug 23 '11 at 20:38

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