[richmarr]

The error bars are massive.

At the CV stage you might be a 6.2, but the error bars on whether you're a good hire might be +/- 5.8.

As you progress you're not just filtering, you're also trying to reduce the massive degree of error.

[brudgers]

I am speaking in terms of accurate measurements...an 8.3 is actually 8.3. Precision is a different issue, but if there are no actual 8.3's in the funnel, then while filtering may improve precision there will never be an actual 8.3 at the narrow end.