On 12-8-2010 15:11, scott wrote:

 > That's because they all think they're one of the best drivers on the 
road,

Warning thread hijacking attempt:
Something that I would have posted on my blog if I had one ;)
I know it is too long, yet there is also much more to elaborate on after 
the last line...
Anyway, inspired by two books: one is 'bad science' by Ben Goldacre, 
apart from using this example wrongly, an interesting read. The other 
book's subject you can guess.
Comments, suggestions and hatemail to the usual address.

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Apparently there was some survey that indicates that 80 or 90% of all 
people think they are a better than average driver. This is often quoted 
as an example of how easy it is for people to fool themselves or some 
similar paternalistic point. I think that says more about the people
that interpret this result, than of the people that participated in this
survey.

There are probably as many driver styles as there are drivers. There is 
for instance the aggressive style, though they would probably describe 
it as 'sporty'. These drivers have good reflexes and know their car so 
well that they are able to put their cars in small gaps that open up in 
a densely packed road. They are often at least 15 seconds earlier home 
than those with a less aggressive style, or so they think. The other end 
of the spectrum are those that have a cooperative style. These drivers 
look around and anticipate what others are going to do, for instance by 
creating a space if they think somebody else is wanting to change lanes. 
It is clear that these two styles will lead to different assessment of 
how good somebody is as a driver. Sporty drivers will consider 
cooperative drivers as slow, stupid and annoying because they don't 
create space fast enough for the sporty ones to let them race on 
uninterrupted. Cooperative drivers will regard the sporty ones as 
homicidal maniacs. Of course the style of driving is not a linear scale 
and other style are possible, for instance one that tries to  inimize 
the amount of gas needed for a trip.
In conclusion, people will try to drive in a way that they think is a 
good driving style and judge other by the same standards. We should have 
been worried if 50% of people would think they are less than average 
drivers on their own scale of what is good driving. The error people 
make when they think that this survey is an example of how people can 
fool themselves, is that they assume that there is an objective 
measurement possible on a linear scale for driving ability.

Let's keep this in mind and see what happens if we *force* a linear 
scale. E.g. assume that there are only a finite number of cars and that 
the government has decided that only the best drivers get a licence. 
First we have to create a committee that can judge drivers capacity. For 
this a natural first group is that group that knows about cars e.g. 
because they own a couple and repair them themselves. This is based on 
the logical assumption that people who know how cars work also know how 
to drive them well. Presumably they will come up with a test like how 
fast drivers can negotiate an obstacle course without damage, to test 
the ability of the drivers. That would indeed create an objective linear 
scale.
So we have as our main ingredients a complex multidimensional concept, a 
need to make it objective and one dimensional, and a group of 
knowledgeable men and what comes out is a very reasonable measure that 
somehow and unplanned is not going to be gender-insensitive. And as long 
as new members of this committee are recruited from the 'best' drivers, 
it will stay that way.

This is of course an imaginary scenario and the fact that so many women 
are going to fail the test is a dead give away that something is wrong. 
You might even argue that no government is going to do something so 
simplistic for such a complex problem. On the other hand many people 
apparently fail to see the fact that driving ability is a 
multidimensional problem to begin with. If you don't, it may seem 
logical that it is a fair and adequate test. There is an even better 
argument that this kind of fallacy is common: it works this way in science

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