The Seven Tenths Theory

(with criticism)

By James J. Baxter, NMA's President

A belief exists among many automotive enthusiasts and, to a large extent, the general motoring public, that driver skill and competence are the true key to highway safety. Unfortunately, neither history nor statistics bear out this heartfelt belief.

For years, the insurance industry has badmouthed high school driver education but their motives have always been transparent. High school driver education makes it possible for many young people to drive at an earlier age than would otherwise be possible. It's generally accepted that young people (especially those who operate solely on hormones and who have not yet converted over to carbohydrates, fats, and proteins) have a lot of accidents.

No report has ever made its way into the NMA office that compared similar populations of drivers and analyzed the accident experience of those who had driver education and those who did not. My guess is there is no difference.

Furthermore, I would be willing to wager that there is no significant difference between the accident experience of persons who take sophisticated driver training courses and those, with the same demographics, who do not.

Consider this: In 1920, we were suffering highway related fatality rates of 25 per 100 million vehicle miles travelled. Today, the fatality rate is 1.8 per 100 million vehicle miles travelled! Is it because we're better drivers? Hardly. In fact, I would argue just the opposite.

The 1920 driver dealt with roadway and vehicle adversities that dwarf the challenges we face today. There were few dilettantes behind the wheel of a Model T. A head-to-head contest between a cross section of 1920 motorists and a cross section of 1993 drivers and our compatriots would be left in the dust, literally.

It's better roads and better vehicles that make the difference. Credit can also be given to standardized rules, the most important being that we all agreed to drive on the right hand side of the road. Remember, this wasn't a given.

So why doesn't driver education and training make a significant difference to highway safety? Because we each modify our driving practices to achieve a certain comfort zone that balances risk and safety, a point that uses seven tenths of our ability.

Adverse conditions or a rare mood may cause us to rachet up or down a notch or two, toward risk or safety. But, by in large, given the choice, we'llstay in the seven tenths range because it provides sufficient stimulus anda sense of reasonable control. However, seven tenths for the experienced autocross enthusiast is different than the seven tenths of a casual 3000 mile per year minivan pilot. And, it shows in the way they each drive.

A given individual's seven tenths threshold also fluctuates based on external and personal conditions. For example, when people drink moderate amounts of alcohol they often slow down and drive more deliberately. They perceive diminished ability and compensate accordingly. (I'm not referring to someone out on a rip roaring drunk.)

Seven tenths in a blinding snow storm is a whole different story than seven tenths on a dry sunny afternoon. The competent and experienced winter driver may drive faster and with greater confidence under adverse conditions. But if he operates at his seven tenths level he is no more or no less likely to have an accident than are less skilled drivers operating at their seven tenths level.

This is simply a derivation of risk compensation theory. As people's skills improve, or diminish, they compensate accordingly. There comes a point where deteriorating skills and physical abilities or impairment reach a level that cannot be fully compensated for. Loss of eyesight, .3% BAC's, and advanced senility are obvious examples of uncompensatable deterioration. However, these are the extremes, not the norm.

Before you sit down to boil off a letter telling me I'm all wet, consider this:

Germany (actually the former West Germany) is renown for its stringent and expensive driver training and testing requirements. However, when comparing fatality rates with the United States, the U.S. is the hands down winner. Autobahn and Interstate fatality rates are quite comparable. But, add in fatality rates for all other streets, roads, and highways and the U.S. exhibits a far lower fatality rate.

All the training and economic discrimination Germany can muster doesn't compensate for a secondary road system originally designed by the Romans for oxcart traffic.

Better driver training can make our system work better, smoother, and faster. But, don't expect big safety payoffs in the process.

Source: September/October 1993 NMA News

You were correct in your article "The Seven Tenths Theory" in the Sept./Oct. issue of NMA News only in that I and probably the other 14,999 members will be telling you that you're all wet. If you did this with tongue-in-cheek to wake up the congregation, then OK, but if you're serious then there is no hope. The good drivers, who strive to be "the best we can be" drivers call on 110%, not 70% of our abilities whenever the occasion calls for it, which is often.

Figures don't lie but liars figure, would just about sum up my evaluation of the "statistics" supporting this theory. And, as for history, I've been driving for 60 years without a chargeable accident as a army and civilian truck driver, professional chauffeur in New York City etc. I've observed the results of the unskilled, incompetent, untrained, uninterested and inexperienced drivers' efforts at "compensating" for their low skill level. So many times they ended up dead or the direct cause of someone else becoming a fatality because they didn't "compensate" correctly, quickly and knowledgeably.

If you haven't stirred up a mess of rattle snakes with this article, I will be surprised. Otherwise, I enjoy the articles and value your organization's efforts on behalf of all of us, motorists under siege.

James F. Angliss
Bellevue WA

The following is in response to your "Seven Tenths Theory" on the relationship between driver skill and fatality rates:

1. It is only logical to assume that a properly trained driver is safer than an untrained driver. The fact that there are no studies to support this assumption is only because there are few if any adequate driver education programs in this country. High school driver education programs are totally inadequate, emphasizing parallel parking instead of real life driving skills.

2. As a graduate of many high performance driver schools, I can assure you that there is a quantifiable improvement in my driving abilities that definitely reduce the likelihood of my becoming a highway fatality. I am also sure that other graduates of these same programs share my belief.

3. Comparison of fatality rates between West Germany and the United States are not relative because of great differences in conditions such as traffic density, weather, topography, vehicle size, variation in traffic speed, etc. Fatality rates in Germany are only relative to other similar European countries with which it compares quite favorably, the lowest in fact. This fact is a result of the very high level of driver training required to obtain a license. German roads, on the other hand, are the world's best. Period. The fact that they are not arrow straight or pancake flat is due to the difficult topography. Judging from you comments I can only assume that you have never visited the country or are incapable of comprehending what exists there. Not to brag, but I have been there 13 times and have driven thousands of kilometers at speeds of up to, and whenever possible exceeding, 150 mph.

Carl Mahrenholz
Palatine IL

I've been meaning to write for a while on various issues, but your "Seven Tenths" theory finally provided the spark to produce action. I liked it!

Reading the column put into words a sense or notion I'd had for a long time but had been unable to express. Good job! I do disagree just a little on your comments about the Germans--you could have carried your basic theory even further in my opinion.

I think that your Seven Tenths theory can be applied to the Europeans: they too operate at a comfort zone, but it's more like nine tenths. As a result, their miscalculations have more serious results. I think that's the main reason for their poorer safety statistics.

Why are they like that? Maybe it's crowded living and the resulting smaller cultural "personal space" envelope. Who know.

Kurt Meyer
Madison WI

I read your article on "The Seven Tenths Theory" and thought it was appropriate to fill you in on some interesting information that we have found at Driving Dynamics (tm).

Driving Dynamics has been in operation since 1987. The parent company, Concept Learning Systems, began in 1983. Between these two companies we have trained over 20,000 students in some form of driver development.

You referenced Germany in your article. I lived in Germany in 1956. I was the first trainee to work at the Porsche factory. I was very familiar with the driver training then and have kept up with it through ADAC since. The type of training that has been provided over the years does not address many of the problems of safe driving.

We are working with psychologists to determine the pressures on and off the job that are major factors in causing accidents. We are developing completely new formats for driver development and reinforcing information after the courses have been taken. Driver development must start with the very basics of driving. If you want to be good you must be taught and you must practice. There are very few self taught athletes in the world. Statistics show that most people have never been taught to drive properly.

The insurance companies would like drivers to begin at age 25. Does this mean that we should put unqualified drivers on the road and experiment for seven years while they get better at everyone else's expense? I say we should train the kids at 17 because their reflexes are good and they are in a learning mode. They are eager to get on the road. If trained properly they can be very good drivers.

Driver development is something that needs to be addressed around the world. If the politicians want to ban something they should ban cars to those who are properly trained. We kill and hurt more people each year with automobiles than we do with guns. When you turn the key in the car it is like loading the gun. In Florida alone, 9 out of 10 kids will have an accident in the first year of driving.

Is there anyone out there who cares? Let's train everyone how to drive well. Let's not just get them their license. Driving can be a very dangerous method of transportation. If you drive a car you must be responsible for all of your actions, learn how to drive properly and take refresher courses. America needs to wake up, it's time to care.

William J. Buff, III
Driving Dynamics Inc.

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