If you can find a good way to put a number on “what people have done”, sure. But if not, I need a way to answer questions like “would giving people chlorine supplements make them more effective at achieving their goals”, and score on IQ test is a) easy to calculate b) at least somewhat correlated with e.g. doing well at one’s job.
Well, once you look at things a bit more subtly, the reason doesn’t seem quite so bad anymore. There is a balance to be struck between the accuracy of the measure and the easiness of calculating it. The most accurate measure is useless if you can’t calculate it. So what’s wrong with using a less accurate measure (but it still works to some extent—you mustn’t look at a) isolation from b)) which you can, in fact, calculate?
The need for balance is a fair point. But then you should make decisions about what to measure on the basis of an explicit trade-off between “easier to get” and “more relevant”—effectively you are using an estimate for the quantity you are really interested in and so you need some support for the notion that your estimate is a reasonable one.
If you can find a good way to put a number on “what people have done”, sure. But if not, I need a way to answer questions like “would giving people chlorine supplements make them more effective at achieving their goals”, and score on IQ test is a) easy to calculate b) at least somewhat correlated with e.g. doing well at one’s job.
That’s actually a bad reason (see the Streetlight Fallacy or the availability bias in general).
Well, once you look at things a bit more subtly, the reason doesn’t seem quite so bad anymore. There is a balance to be struck between the accuracy of the measure and the easiness of calculating it. The most accurate measure is useless if you can’t calculate it. So what’s wrong with using a less accurate measure (but it still works to some extent—you mustn’t look at a) isolation from b)) which you can, in fact, calculate?
The need for balance is a fair point. But then you should make decisions about what to measure on the basis of an explicit trade-off between “easier to get” and “more relevant”—effectively you are using an estimate for the quantity you are really interested in and so you need some support for the notion that your estimate is a reasonable one.