Sunday, December 10, 2006

risk / safety tradeoff

We have known for a long time that many safety features do not actually make people safer because they use this opportunity to work faster/riskier/etc and thus revert to the individual's own risk tolerance (modified by external incentives such as productivity bonuses).

But there are also negative externalities to worry about. In a new study, Ian Walker at the University of Bath found that cyclists who wear helmets have a higher chance of getting hit by a car than those who do not. So does this mean that cyclists adjust to their added safety by riding more aggressively? It turns out the answer is no. The people who adjust their behavior is the driver. Drivers passing cyclists with helmets drive closer to the bike than drivers passing cyclists without helmets. So even though the biker doesn't change his/her behavior, his/her risk goes up.

An earlier study by Sam Pelzman found that drivers who wear seat belts drive more aggressively. So their risk stays the same overall. But the people around them have higher risk. So the total system risk is higher. Paradoxically, adding safety features increases total system risk.

There is not enough data to know how significant this effect is in general or whether it would really be better to get rid of some safety features to increase safety. Sounds like a good research proposal for an ambitious safety researcher.

Human Factors and biblical interpretation

I had a very interesting conversation with some students last night. Normally, I don't like to bring up religion at dinner because it tends to be an emotional topic. But one student seemed really interested in my view, so I thought I would share it with her. I was explaining that something in the brain's function likely evolved because of the needs of humans as the emerged from the African savannah.

She asked me if I believed in evolution or creation. I told her both, and the explanation is pure human factors. I believe that G-d created evolution. It makes much more sense to set in place a system of physical laws and cosmic raw materials than it does to preset each and every species of animal and plant.

So the next question of course is "Why does it say in the bible that it took six days etc?" But this is where human factors comes in. Imagine the state of human knowledge at the time that G-d was explaining the history of the world to Moses on Mt Sinai. Moses would not have understood any of it. I am sure that G-d would have loved to explain how the double helix structure of DNA leads to natural selection, but it would not have been a good use of time. So he explained in using stories in the same way that scientists explain their work to their families, or parents explain sex to young children. And then Moses told the rest of the Hebrews, who told their kids, who told their kids etc for about 1500 years before anyone wrote it down.

Given this reality, it is remarkable how many things do fit the historic record, not the several inconsistencies. When my students copy class notes from friends after they miss a class, there are huge discrepancies. I can't imagine going 1500 years without the content changing completely.

So, G-d created evolution, told Moses the story allegorically in a way he could understand, and 1500 years later, we get Adam and Eve, Noah's flood, etc. I don't see how it could be any other way.