(Originally posted to my blog, The Rationalist Conspiracy; cross-posted here on request of Lukeprog.)

You’re the captain of a team, and you want to select really good players. How do you do it?

One way is through what I call positive selection. You devise a test – say, who can run the fastest – and pick the people who do best. If you want to be really strict, like if you’re selecting for the Olympics, you only pick the top fraction of a percent. If you’re a player, and you want to get selected, you have to train to do better on the test.

The opposite method is negative selection. Instead of one test to pick out winners, you design many tests to pick out losers. You test, say, who can’t run very well when it’s hot out, and get rid of them. Then you test who can’t run very well when it’s cold out, and get rid of them. Then you test running in the rain, and get rid of the losers there. And so on and so forth. When you’re strict with negative selection, you have lots and lots of tests, so that it’s very hard for any one person to pass through all the filters.

I think a big part of where American society’s gone wrong over the last hundred years is the ubiquitous use of negative selection over positive selection. (Athletics is one of the only exceptions. It’s apparently so important that people really care about performance – as opposed to, say, in medicine, where we exclude brilliant doctors if they don’t have the stamina to work ninety hours a week.) A single test can always be flawed; for example, IQ tests and SATs have many flaws. However, with negative selection, how badly you do is determined by the failure rate of every test combined. If you have twenty tests, and even one of them is so flawed it excludes good players, then your team will suck.

Elite college admissions is an example of a negative selection test. There’s no one way you can do really, really well, and thereby be admitted to Harvard. Instead, you have to pass a bunch of different selection filters: Are your SATs good enough? Are your grades good enough? Is your essay good enough? Are your extracurriculars good enough? Are your recommendations good enough? Failure on any one step usually means not getting admitted. And as competition has intensified, colleges have added more and more filters, like the sup...

NiklasF

NiklasF

NiklasF

NiklasF