When examining an employment test, courts use the following categories (ranked in order of lessening confidence by the courts):
1. Content validity: does the exam test the kind of work actually done?
2. Construct validity: does the exam test the skills needed by a worker?
3. Criterion validity: does the exam tend to correlate with better, more successful workers, regardless of what skills are tested?
- Courts tend to get nervous if you can't explain why, even if they technically have to accept the result
- Plus remember the potential rebuttal by employees in a suit: if the employee can show a method is as efficacious as the one you've chosen, but that is less discriminatory, the defendant loses!
Note: any time you use rank-order testing (such as focusing on how much someone can bench press) and then say it helps pick the best worker (such as a firefighter) you are ignoring all the other important skills that go into that job, opening yourself up as an employer to attack on that basis.