Managing validity versus reliability trade-offs in scale-building decisions

Scale builders strive to maximize dual priorities: validity and reliability. While the literature is full of tips for increasing one, the other, or both simultaneously, how to navigate tensions between them is less clear. Confusion shrouds the nature, prevalence, and practical implications of trade-offs between validity and reliability-formerly called paradoxes. This confusion results in most trade-offs being resolved de facto at validity's expense despite validity being de jure the higher priority. Decades-long battles against clear measurement malpractice persist because unspecified trade-offs render scale-building decisions favoring validity perennially unattractive to scale builders. In light of this confusion, the goal of this article is to make plain that the source of validity versus reliability trade-offs is systematic error that contributes to item communality. Moreover, straightforward, nontrivial trade-offs pervade the scale-building process. This article highlights common trade-offs in 6 contexts: item content, item construction, item difficulty, item scoring, item order, and item analysis. I end with 5 recommendations for managing trade-offs and out 7 "dirty tricks" often used to exploit them when nobody's looking. In short, reviewers should require scale builders to declare how validity and reliability will be prioritized and penalize those who resolve trade-offs in goal-inconsistent ways. (PsycInfo Database Record (c) 2020 APA, all rights reserved).