Tim Harford has an interesting article on the murkier side of transparency – i.e. how more information is not always better.
For example, he talks about how Toronto installed countdown timers at various traffic signals, giving pedestrians an idea of how many seconds they have to cross the road. Since they installed these signals on only some intersections and not others, some researchers used this opportunity to study the impact of the timers on the accident rate.
You might well anticipate that the countdowns would make junctions less dangerous, by telling pedestrians whether or not they have time to cross in safety. Toronto’s traffic planners certainly seemed to believe that would be the case. They were wrong. The new signals caused more accidents.
How is this possible? Here is the suggested explanation:
If a signal is about to turn red for pedestrians crossing at a junction, then drivers who are trying to get across the junction in the same direction are also about to get a red light. Since there was more speeding and more rear-end collisions after the countdown signals were installed, Kapoor and Magesan reckon the natural explanation is that some drivers were accelerating into the junction to avoid being delayed, just as other drivers were slowing down.
This idea, that more information can actually hurt, shows up in other places too. Here is an example of a study conducted on hospitals which insisted that success rates of individual doctors/surgeons be published.
Ten years ago, David Dranove, Daniel Kessler, Mark McClellan and Mark Satterthwaite looked at the impact of mandatory “report cards” in New York and Pennsylvania, which published data on the performance of individual doctors, hospitals or both.
One might imagine that this information would, at the very least, be convenient. At best it should spur physicians to improve their skills because patients would seek out the very best. But the researchers looked at the impact on cardiac surgery, and found a tragic side effect: once doctors and hospitals knew that their success rates would be published, they had a strong incentive to operate on the healthiest patients. The best hospitals had their pick of the sick and selected easy cases. Meanwhile patients with more complicated conditions were more likely to have surgery postponed. The net result: more money was spent, yet more people died of heart attacks.
In other words, sometimes it pays to make information available only selectively:
Publishing clear information is often a way to make the world a better place – but not always. Sometimes it pays to be selective. Doctors could benefit from report cards, provided their patients never find out what they said. And Toronto’s countdown signals would work perfectly if only they could be hidden from drivers.
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