> 4) As I said above, if you read the actual case, the facts were that the test did not predict success at the job. This turns out to be very common.
This does not mean the test isn't a good test in the sense that it doesn't measure job performance. See how there is no correlation between a players height in the NBA and how well they perform. This is because if there was a correlation then selectors would be leaving money on the table and they could improve their selection for the coming year by increasing the weighting on height (compared to everything else), which would in turn reduce the amount of correlation. Rinse and repeat until there is no correlation left.
The test not predicting job performance could equivalently mean that Duke Power had a very well calibrated way to choose their employees where they were prefectly capturing the information from the apitutde test compared to all the other factors involved in hiring. Indeed the fact that this turns out to be very common suggests to me that this is going on here (and elsewhere).
Excellent. Call it Hartgood's law: a measure used for control purposes is worthless for observing statistical regularities in the phenomenon being measured in proportion to how optimal the control is.
> 4) As I said above, if you read the actual case, the facts were that the test did not predict success at the job. This turns out to be very common.
This does not mean the test isn't a good test in the sense that it doesn't measure job performance. See how there is no correlation between a players height in the NBA and how well they perform. This is because if there was a correlation then selectors would be leaving money on the table and they could improve their selection for the coming year by increasing the weighting on height (compared to everything else), which would in turn reduce the amount of correlation. Rinse and repeat until there is no correlation left.
The test not predicting job performance could equivalently mean that Duke Power had a very well calibrated way to choose their employees where they were prefectly capturing the information from the apitutde test compared to all the other factors involved in hiring. Indeed the fact that this turns out to be very common suggests to me that this is going on here (and elsewhere).
Excellent. Call it Hartgood's law: a measure used for control purposes is worthless for observing statistical regularities in the phenomenon being measured in proportion to how optimal the control is.