The personality/preference tests are intended to evaluate a prospective employee's suitability for a particular position. They are not a measure of "competency" at any particular task. The IQ test is not intended to measure "knowledge", but rather to gauge the applicants ability to reason and learn.

It's probably safe to say that an employment decision is not based on any single test, but rather on the complete picture painted by all these tests as well as the interview, references and background checks.