Short Versus Long Scales in Clinical Assessment: Exploring the Trade-Off Between Resources Saved and Psychometric Quality Lost Using Two Measures of Obsessive-Compulsive Symptoms.

Short measures of psychological constructs are routinely used to save assessment time and cost. The downside is a trade-off between resource savings and psychometric quality. When evaluating tests, a pragmatic strategy is frequently applied that neglects the assessment objective, which may result in unfair rejection or unmindfully acceptance of short scales. Our main aim is to demonstrate the consequences of applying a pragmatic test evaluation strategy. We used two tests that measure the same construct-obsessive-compulsive symptomatology-but differ considerably in test length (1:3) and evaluated the measures by taking the assessment objective into account. The two scale scores showed distinct profiles of psychometric qualities. Whereas routinely evaluated reliability, factorial validity, and convergent/discriminant validity did not differ, rendering both tests useful for research purposes, substantial differences were found for qualities that are rarely focused on-measurement precision and diagnostic validity-which are highly relevant for accurate decisions in clinical practice.