Different position with different demands and different statistical characteristics. (justarsenal.com)
The agencies select statistical characteristics found in a person's credit payment patterns, analyze them and come up with a credit score. (debt.org)
Each student gets a more or less random sample of items, some students will get a bunch of hard ones, some will get easy ones, in fact the test developer doesn't know yet which items will be hard or which ones will be easy, and in fact the expectation is that roughly half the items in the study will not have the right statistical characteristics to survive and be included in the final operational tests anyway. (edsource.org)