Tautology trap

A validation in which an instrument’s items and the criterion it is measured against are drawn from one construct, so the correlation between them was determined at authoring time and reports the wording rather than the world. The limiting case of criterion contamination, which requires a leak between predictor and criterion; the tautology requires no leak, because the two were never independent. Distinct from the borrowed ruler, which concerns whose population calibrated the scale. The contemporary instance is an evaluation that asks a rater whether a response was helpful and reports the aggregate as evidence of helpfulness.