This is it. The day to traipse to the post office and mail in your income tax papers. In farm lingo, this is the time swill the pigs. To feed the beasts. To oil the machine. To encourage the greedy sons-of-you-know-whats. To unwilling fork over what the politicians think belongs to them.
Unless you’re one of the lucky few—and by “few” I mean half of all Americans—who don’t have to pay federal income taxes, today is the day you’ll have to donate over a large chunk of your income to insatiable Washington bureaucrats. This can lead to a certain amount of “stress.” And that modern malady can cause you to drive distractedly. Which in turn can cause you to die in a bloody, fiery crash.
Or so says Donald Redelmeier and Christopher Yarnell who published a peer-reviewed research letter in JAMA which claims to have statistical proof that traffic accidents increase on Tax Day.
Taxes, our pair says, “influence the long-term health of the economy,” but how do taxes affect the health of people?
We investigated the number of individuals involved in a fatal road crash on tax day under the prespecified hypothesis that stressful deadlines might increase the risk of road trauma by impairing drivers or by compromising surrounding individuals from making compensatory adjustments.
They looked at each Tax Day from 1980 to 2009 (30 years; though the data extend to 1975; why leave it out?), and the two days a week before and after Tax Day, and counted the number of fatal crashes, defined as at least one person crapping out because of and within 30 days of the crash. There were 6,738 fatal crashes on tax day and 12,758 fatal crashes on the other two days. Conclusion?
Comparisons of tax days with control days yielded an odds ratio of 1.06 (95% CI, 1.03-1.10; P < .001), equivalent to an absolute increase of 404 individuals in fatal road crashes on tax days over the study interval or about 13 individuals during the average tax day.
So if Redelmeier is right, driving to the post office in a state of high dudgeon on Tax Day kills about 13 Americans each year. As the good doctor said in a news report on this study, “Who looks to tax day in a joyful way? Even those who are getting refunds are stressed. Refunds are never as big as they thought and there is always the chance they could be reviewed at a later date.”
That 1.06 appears to arise from ( 6738/30 ) / ( 12758/60 ), incidentally. Ignore the p-value, because with sample sizes this large publishable p-values are free for the asking. Focus instead on the reasons our researchers gave:
One explanation is that stressful deadlines distract drivers and contribute to human error (a national poll suggested that tax day was the second most stressful day in 2011)…Driving patterns may be altered on tax day. Although
electronic submissions might be expected to lessen driving on tax day, we observed an increase rather than a decrease in fatal crashes in recent decades.
Now isn’t that odd. E-filing—that is, the non-necessity of driving to the post office—accentuates the effect. Somehow. Who knows how. But, as the saying goes, the numbers don’t prevaricate.
We always knew road crashes destroyed the lives of thousands of people each year in the U.S., and driver error contributes to 93% of the crashes. Stress is often speculated to contribute to driver error, but stress is usually impossible to study, [but] tax day is synchronized, repeated, and tremendously onerous…
Almost every one of these fatal crashes could have been avoided by a small change in driver behavior.
Tax Day isn’t the only danger, no sir. The good doctor, who is a kind of crash aficionado, has in other work also identified Super Bowl Sunday and Election Day1 as killers. Yes, I know what you’re thinking, but you’re wrong: the risk of crashing on Election day “was similar, regardless of whether a Democrat or Republican was elected.” His research also “does not indicate which candidate could best help save the 100 lives lost each day in fatal crashes in the United States.”
Redelmeier has also, in the same statistical manner, “discovered” that emergency department visits decreased during an Olympic gold medal television broadcast. This reminds me of the apocryphal story I used to hear as a kid: that water use surged during commercials in the I Love Lucy program.
The way to criticize these studies is so obvious that I leave it as a homework exercise in the comments. (Plus, I may shortly have a way to investigate the numbers.)
Thanks to DAV for suggesting this topic.
1This paper was published with Rob Tibshirani, a good statistician and aggressive if not unskilled basketball player. But nobody bats 1.000.