Sunday, April 3, 2011

Further Proof of White Noise Syndrome

We have commented in previous posts about a phenomenon we like to call "White Noise Syndrome", or the shifting of deaths from one age group to another when the drinking age is changed.  Sociologist Mike Males refers to this as a "seesaw effect".  This has been documented in several peer-reviewed studies, namely Males (1986), Asch and Levy (1987 and 1990), and most recently in Dee and Evans (2001).  Studies like Carpenter and Dobkin (2010) which find increases in deaths upon turning 21 (today, with a 21 drinking age) seem to dovetail with these results.  Of course, as with anything not every study has agreed with these results, and estimates of net effects varied, but they have been pretty tough to refute. 

Now a new study by economics student Dan Dirscherl (2010) at Notre Dame University further confirms the previous studies mentioned.  His award-winning paper, which uses a fixed-effects, difference-in-differences model on data from 1972-1994 finds that a drinking age of 21 (compared with a lower one) not only shifts deaths from 18-20 year olds to 21-24 year olds, but appears to result in a net increase in fatalities among 18-24 olds.  The effect was driven by males, while females saw no effect either way.  Interestingly, the effect on 18-20 year olds was statistically insignificant, while on 21-24 it was highly significant.  This is the dirty (not to mention deadly) secret of the supposed lifesaving effect of the 21 drinking age that the pro-21 crowd would rather sweep under the rug. 

One potential flaw to this study was that legal drinking ages of 18 and 19 (and even 20 for two states) were lumped together as states with an age limit below 21, compared with states at 21.  This could increase the noise in the data.  However, Miron and Tetelbaum (2009) found no statistically significant difference between drinking ages of 18, 19, or 20 on traffic fatalities in any of their models, even those models that found significant effects for a drinking age of 21 relative to 18.  (Of course, the best model found no lifesaving effects in the long run for MLDA 21 either.)  Another criticism one could make is that Dirscherl did not include data for those under 18.  Again, however, Miron and Tetelbaum found during a robustness check of their own study that a drinking age of 19, 20, or especially 21 increases fatalities of drivers under 18, contrary to what the "trickle-down" or "low-hanging fruit" theory predicts.  Still another criticism is that Dirscherl (like Miron and Tetelbaum) used total traffic fatalities and not "alcohol-related" ones.  But there is no reliable data for "alcohol-related" fatalities before 1982, and even after that the data can be biased due to differences in testing rates.  When using data going that far back, when about 2/3 of teenage fatalites were alcohol related, total fatalities would likely be sufficient, but surrogates like single-vehicle nighttime fatalities are a good robustness check.  And both studies by Asch and Levy do exactly that, with similar results. 

Of course, alcohol-related deaths among young people are by no means limited to the highways.  There is virtually zero evidence that non-traffic alcohol-related fatalities as a whole are significantly reduced by the 21 drinking age, and effects on specific causes of non-traffic death have been inconsistent at best.  In fact, from 1998 to 2005 (years during which enforcement of the 21 drinking age generally increased), these fatalities among 18-24 year olds increased significantly, including a near-tripling of alcohol poisoning deaths for this age group.  It is entirely plausible that forcing alcohol use underground for 18-20 year olds would make it more dangerous than it has to be, most notably for alcohol poisoning deaths (which are really just the tip of the iceberg of high-risk drinking).  An honest cost-benefit analysis of the 21 drinking age should take these deaths into account as well.

We did our own research as well, using the CDC WONDER database to look up any deaths that mentioned "alcohol" in the cause of death for 15-24 year olds.  They group ages by 15-19 and 20-24 instead of 18-20 and 21-24, but the data are still useful for our purposes.  Shown below are the alcohol-related death rates per million people in each of the two age groups.

In other words, raising the drinking age to 21 appears to have been a shell game at best, and those who support it have quite a bit to answer for.  It's a lot like the movie White Noise 2, hence our term for this unfortunate phenomenon.

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