MMJ laws associated with 9% drop in traffic fatalities

[Telarus]

Cause I'm an asshole who won't let this issue go. (Note: "Correlation does not equal causation" and all that...)

http://www.iza.org/en/webcontent/publications/papers/viewAbstract?dp_id=6112

Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption
by D. Mark Anderson, Daniel I. Rees
(November 2011)

Abstract:
To date, 16 states have passed medical marijuana laws, yet very little is known about their effects. Using state-level data, we examine the relationship between medical marijuana laws and a variety of outcomes. Legalization of medical marijuana is associated with increased use of marijuana among adults, but not among minors. In addition, legalization is associated with a nearly 9 percent decrease in traffic fatalities, most likely to due to its impact on alcohol consumption. Our estimates provide strong evidence that marijuana and alcohol are substitutes.

Text: See Discussion Paper No. 6112

[Telarus]

GODS. finally got through the 1st 22 pages of this thing (had to dust off some of my statistics math to understand some of it).

Finally got to the summary, tho. Here we are:

Although popular, medical marijuana laws have received minimal scrutiny from
researchers. In fact, next to nothing is known about their impact on outcomes of interest to
policymakers, social scientists, advocates, and opponents.

The current study draws on data from a variety of sources to explore the effects of
legalizing medical marijuana. Using data from the National Survey on Drug Use and Health
(NSDUH), we find that the use of marijuana by adults in Montana and Rhode Island increased
after medical marijuana was legalized. Although opponents of legalization argue that it
encourages recreational use among teenagers (Brady et al. 2011; O'Keefe and Earleywine 2011),
we find no evidence that the use of marijuana by minors increased.

Using data from the Fatality Analysis Reporting System (FARS) for the period 1990-
2009, we find that traffic fatalities fall by nearly 9 percent after the legalization of medical
marijuana. This effect is comparable in magnitude to those found by economists using the FARS
data to examine other policies. For instance, Dee (1999) found that increasing the minimum
legal drinking age to 21 reduces fatalities by approximately 9 percent; Carpenter and Stehr
(2008) found that mandatory seatbelt laws decrease traffic fatalities among 14- through 18-yearolds
by approximately 8 percent.

Why does legalizing medical marijuana reduce traffic fatalities? Alcohol consumption
appears to play a key role. The legalization of medical marijuana is associated with a 6.4 percent
decrease in fatal crashes that did not involve alcohol, but this estimate is not statistically
significant at conventional levels. In comparison, the legalization of medical marijuana is
associated with an almost 12 percent decrease in any-BAC fatal crashes per 100,000 licensed
drivers, and an almost 14 percent decrease in high-BAC fatal crashes per 100,000 licensed
drivers.

The negative relationship between legalization of medical marijuana and traffic fatalities
involving alcohol is consistent with the hypothesis that marijuana and alcohol are substitutes. In
order to explore this hypothesis further, we examine the relationship between medical marijuana
laws and alcohol consumption using data from the Behavioral Risk Factor Surveillance System
and The Brewer's Almanac. We find that the legalization of medical marijuana is associated
with decreased alcohol consumption, especially by 20- through 29-year-olds. In addition, we
find that legalization is associated with decreased beer sales, the most popular alcoholic beverage
among young adults (Jones 2008).
[Oh, well that explains all the money the beer industry dumped to propaganda against Cali's Prop 9. A 6% drop in sales directly eats into their profit margin! (see page 10/11 of that link... the only thing the industry wonks consider a "direct substitute/alternative" to Beers sales is Wine and Liquor!) -Tel]

Evidence from simulator and driving course studies provides a simple explanation for
why substituting marijuana for alcohol may lead to fewer traffic fatalities. These studies show
that alcohol consumption leads to an increased risk of collision (Kelly et al. 2004; Sewell et al.
2009). Even at low doses, drivers under the influence of alcohol tend to underestimate the
degree to which they are impaired (MacDonald et al. 2008; Marczinski et al. 2008; Robbe and
O'Hanlon 1993; Sewell et al. 2009), drive at faster speeds, and take more risks (Burian et al.
2002; Ronen et al. 2008; Sewell et al. 2009). In contrast, simulator and driving course studies
provide only limited evidence that driving under the influence of marijuana leads to an increased
risk of collision, perhaps as a result of compensatory driver behavior (Kelly et al. 2004; Sewell et
al. 2009).

However, because other mechanisms cannot be ruled out, the negative relationship
between medical marijuana laws and alcohol-related traffic fatalities does not necessarily imply
that driving under the influence of marijuana is safer than driving under the influence of alcohol.
For instance it is possible that legalizing medical marijuana reduces traffic fatalities though its
effect on substance use in public. Alcohol is often consumed in restaurants and bars, while many
states prohibit the use of medical marijuana in public.35 Even where it is not explicitly
prohibited, anecdotal evidence suggests that the public use of medical marijuana can be
controversial.36 If marijuana consumption typically takes place at home, then designating a
driver for the trip back from a restaurant or bar becomes unnecessary, and legalization could
reduce traffic fatalities even if driving under the influence of marijuana is every bit as dangerous
as driving under the influence of alcohol.
[That's a GREAT line. -Tel]

Finally, an important caveat deserves mention. Our classification of states into those that
allow the use of medical marijuana and those that prohibit its use does not capture potentially
important factors such as whether formal registration with the state is compulsory or voluntary,
what types of ailments are covered, and whether an official dispensary system is in place. While
measuring these differences and their impact is beyond the scope of this study, future research
could explore the nuances of these laws.

[/size]


And then there's 5 pages of citations and 17 pages of tables. Worth reading through if you're interested (and can ignore when the statistics math gets too complex to follow coherently HAH).

[AFK]

Interesting.  I would be interested to see a study that looks at state level data, in relation to consumption by minors.  That is, the state level data from state-generated surveys.  The NSDUH and BRFSS can be useful instruments when looking at national trends, but in my experience, they aren't as good at looking at state level trends compared to state generated tools because the sampling isn't as precise. It is certainly precise for looking at the national picture, but I don't think it holds firm when you get down to the state level.  But even there, I'd put money on an increase in minor use in the 2011 data in my state, and that data should be out sometime this month. 

[Dysfunctional Cunt]

 



Why? 

[Telarus]

Why? 

Because, according to their stats, there are ~21 less grieving families per year for every 1,000 registered drivers in a state that has MMJ laws compared to directly neighboring states which don't (with no increase in minor consumption).


It's not often you can nail down a clear association like that.

[rong]

so what you're saying is: LEGALIZE IT, OR PEOPLE WILL DIE!!!!

[Telarus]

so what you're saying is: LEGALIZE IT, OR PEOPLE WILL DIE!!!!

[BabylonHoruv]

so what you're saying is: LEGALIZE IT, OR PEOPLE WILL DIE!!!!

And some of those people will be children!

[Bebek Sincap Ratatosk]

Interesting study, thanks for the link Telarus!