Who Drives Better, Men or Women?

We’ve established that men are more likely to take the wheel when a couple rides together, but should we care? I say we should. Aside from the cultural, sociological and psychological implications, the gender driving disparity might be costing us lives and treasure. If women are more skilled drivers than men, perhaps we’d all be better off if they were behind the wheel and men were in the passenger seat knitting. What do the data say?

Despite comprising half the population, women drivers are unquestionably involved in many fewer accidents than men are. In fact, it isn’t even close. Insurers are well-aware of this fact (see this from the Australian insurance company AAMI), and hence they often charge women lower premiums.

So there it is: women have fewer accidents than men. Time to move the driver’s seat up?

Not quite-we haven’t yet heard the whole story (and we all know that once that seat is moved? you can never again get it as comfortable as you once had it).

The problem is that if we’re trying to determine whether men or women should take the wheel when the couple is in the car, aggregate accident totals are of limited usefulness.

Why? Because men drive lots more than women do. The American Time Use Survey shows that adult men average about 60 minutes a day behind the wheel, while women average around 40. The National Household Transportation Survey reports that in 2001 men averaged 16,749 miles driven per year, and women 10,174. Given that they drive so much less, it’s not particularly surprising that women are involved in fewer accidents and pay lower premiums.

To really answer our question we need to look at data adjusted for “exposure,” that is, the amount of time people spend behind the wheel. In our case, what we’re looking for is accidents per mile driven.

Research (gated) by Guohua Li, Susan P. Baker, Jean A. Langlois and Gabor D. Kelen showed that, as of the mid-1990s, women drivers were involved in about 5.7 accidents per million miles driven. Men, on the other hand, were involved in about 5.1. Women were thus 12 percent more likely to be in crashes per mile driven. This is confirmed by another paper (gated), by Dawn L. Massie, Kenneth L. Campbell, and Allan F. Williams, which found women were involved in 16 percent more accidents than men on a per mile driven basis.

We might want to think not just about accidents, but about the severity of those accidents. Here again, it doesn’t look good for the ladies. Massie et al. found that for each mile driven women were 26 percent more likely than men to be in crashes involving injuries.

So there we have it; with men having fewer accidents and fewer injury accidents per mile, all those women driver jokes from my grandparents’ generation can be dusted off and put to good use.

Or can they be?

If we move to the next level of severity, fatal accidents, we find quite a different picture. Li et al. found that male drivers are 80 percent more likely to be in a fatal accident than women on a per mile basis. Massie et al. confirmed this, finding men are 55 percent more likely to be in fatal crashes. More recent data,?collected by the Insurance Institute for Highway Safety, paints an almost identical picture.

Thus women are somewhat more likely to be in crashes, but men are lots more likely to be in very severe crashes. According to AAMI:

Men are more likely than women to be involved in serious accidents – that is, men experience more head-on collisions, roll-overs, loss-of-control crashes and collisions involving pedestrians, cyclists or animals whereas women are more likely than men to collide with stationary objects or reverse into other cars.

So if saving lives is our goal, perhaps it’s time the women take the wheel, and we allocate transportation stimulus funds to a team of comics to craft an all-new set of male driver jokes to be used by future generations.

Well, maybe. Even given these data, a number of factors might be clouding the picture. For one thing, I don’t have data on who was at fault in accidents (one study had this but didn’t do per mile exposure). I suppose it’s possible that one sex or the other has a greater propensity to be the innocent victim in accidents, but it strikes me as unlikely.

Another complicating factor could be the driving environment. For example, Jeff Wise, author of Extreme Fear: The Science of your Mind in Danger, has blogged in this space about the fact that freeways are considerably safer than surface roads. If men do a higher share of their driving on the freeways (and I suspect that this is the case due to differing commuting patterns), this would make them appear to be less dangerous drivers than they really are. Also, it’s possible that since men do most of couples’ driving they are more likely to be behind the wheel at night when visibility is poor.

In this vein, another possibility is that the tradition of the man driving is keeping the truly terrible female drivers off the road, and thus our population of women drivers exhibits selection bias. In that case, handing women who don’t currently drive the keys might have exactly the opposite of the intended effect.

In any event, to truly understand this issue we need to dig a bit deeper to find not just the numbers, but the reasons for what’s going on. More on this coming up.


Craig

But these studies haven't compared married (or at least cohabitating) men vs. married women. Unmarried men are far likelier to be in an accident than married men. Thus, we still don't have the data we need to examine which should drive, the husband or wife.

RAG's.....

Dear Lisa;

You have a good point, My husband complains all the time about my lack of focus (caused by doing too many things at once). I have my daughter on a strict regimen now of single minded effort to get into the college of her choice. So my advice to parents- Stop your child from blogging, watching tv, twittering all at once while doing homework.

Zack

Men are better drivers but they just have a lot more testosterone.

N.B.

Where does experience come into play here?
I mean if we assume more experienced driver is less likely to get into an accident, shouldn't we factor out experience and ask in each category, given the number of total miles driven, who is more likely to have had accidents?
From all that is said, it seems like women drive more city miles(less damaging accidents, less miles drive) and men more highway miles(faster speeds, fatal crashes, less accidents).

--E

Another factor is that people get better at things they practice more often. Perhaps if women drove as much as men (on average), they would improve.

I know the most frustrating thing for me as a driver is being behind someone who doesn't seem to understand how their indecision is screwing up the traffic. I haven't done a survey of their gender, but I think it's safe to say they're not likely people who get a lot of practice behind the wheel.

I've been driving for 24 years, and haven't had an accident in the past 23 of them. I'm a woman who would never hand over her car keys to anyone unless I was physically unable to drive.

Lynn

Also to take into account: at least for young people, having a male passenger in the car makes the driver worse.
http://www.cdc.gov/motorvehiclesafety/teen_drivers/teendrivers_factsheet.html

Brian

Taking off on Kristine's and Ace's points: accidents are one cost of a bad driver, but bad drivers also impose other costs on the rest of us, namely delay.

Aggressive drivers and lane jumpers slow the overall speed of traffic. Slow drivers cause the same problem. It'd be interesting to quantify these costs and explore any gender differences.

Remo

When Better means Safer, women ought to be better drivers. Women are more responsible than men in all walks of life, be it education, health, or social norms.

RAG's.....

Dear Mike;

This will be my last re-mark for today. But I do think that it's about real differences between us that may be unavoidable and impossible to overcome? Having two drivers in a family therefore may well be a good thing. When you don't, knowing your limitations is about the best one can do to avoid a crash. I have learned this lesson the hard way i.e., as in don't drive while upset.

avirr

So... basically you are saying that despite the blog post title, there's no clear favorite: female and male drivers have slightly different outcomes, and it all matters which statistic you choose. what answer you get. Which is about how I feel about pretty much all male vs. female issues.

Tough Love

Dear Avirr;

No- it is not only about the fact that men and women are better at doing different things and to that extent men and women have revealed themselves to be capable of learning from one another, but that there is one thing that women seem to be able to do that men (not even one truly gifted creative man) cannot.

The first time I drove with my future husband on a vacation testifies to this fact. 3 hours into the trip, he was convinced that it would just take a little bit longer to get there. 2 1/2 hours later we arrived exhausted by the continual thought that just a little more time would be enough to reach our actual destination. That's why I always have to remind myself not to rely upon my husband for directions. He's great when it comes to matters of expediencey, but I continually need to keep myself abreast of the situation and thus my eye on the mark.

Daniel

This is exactly what anybody would've guessed based on common sense stereotypes, which is that women drive less and tend to be less skilled at driving, but men, particularly unmarried young men, are much more likely to choose to engage in very risky driving behavior associated with fatal accidents (such as driving extremely fast or deliberately flouting the rules of the road).

Jonathan

Males could also be involved in more serious accidents because of their ego. Many males feel like they have to show that they are the alpha male of the road and this can put them in more dangerous situations.

David

The information is very intriguing to me. Could you say from the information provided that a woman's tolerance level to pay attention to the road is shorter than men? Does this mean women are more distracted than men as well?

juda

"I suppose it's possible that one sex or the other has a greater propensity to be the innocent victim in accidents, but it strikes me as unlikely" you are dead wrong of course the cautiousness of the driver and there reflex speed will effect things and this is probably effected by gender

htb

Is per-mile a better measurement than per-trip?

I know several men who drive more miles than their wives -- but who also make exactly two 'trips' each weekday: forty miles to the office, and forty miles back again.

Their wives, on the other hand, drive to and from the kids' school twice a day (yes, it's California, the state that thinks it's cheaper to send 500 minivans and 500 parents to the local school twice a day, at an average cost of 30 minutes per round trip, than to hire 10 school buses), plus sports and music lessons, plus all the shopping and other errands.

It seems like this should be evaluated in a similar fashion as "Is it safer to drive, or to fly?"

Chris in Baltimore

As a number of other commenters have suggested, you absolutely MUST control for sobriety and age.

Rita@Goldivas

"Another factor is that people get better at things they practice more often. Perhaps if women drove as much as men (on average), they would improve."

Absolutely. I am a single woman and I avoid riding with married women because they don't get as much practice, and do tend to be indecisive. Single women are better drivers.

Mike

I wonder if one factor causing the disparity between accidents and fatal accidents is seat belt use. Are men less likely to use seat belts than women and therefore more likely to be involved in fatal crashes? I would also suspect that men are far more likely than women to drive while drunk.

The results do jibe with my instincts -- that women are more likely to take out the mirror on the side of the house (especially if kids are in the car) but men are more likely to drive into a tree. But I'm leery of confirmation bias.

Kyle

Uh, many researchers have known this accidents-per mile driven figures for over a decade. This isn't really "news."