Abstract / Summary
Abstract Objective: The Nationwide Quality of Life Scale (NQLS) is a brief, public-domain, youth self-report measure designed for quality of life (QoL) reporting in measurement-based care (MBC). Preliminary psychometric support comes from a sample of treatment-seeking youth, but its use in a population-based sample has not been evaluated. This study examined the NQLS psychometric performance in a U.S. nationally representative sample and develops national norms, score interpretation guidance, and clinical significance benchmarks. Method: A nationally representative sample of 1,008 youth ages 12-18 completed the NQLS as part of a larger survey battery. Analyses included exploratory and confirmatory factor analysis, reliability, validity, item response theory, and generalized additive models for location, scale, and shape (GAMLSS) norming. We integrated these results with clinical data from 1,200 youth seeking treatment at a large Midwestern children's hospital to estimate clinical significance benchmarks and compare between groups. Results: One- and two-factor solutions were evaluated. The NQLS demonstrated good internal consistency and convergent validity, with distinguishable 'life' and 'school' factors. Normative percentiles were generally stable across age, with modest narrowing at the youngest and oldest ages. Normative-sample youth showed raw score and latent trait estimates significantly higher than clinical-sample youth. Conclusions: The NQLS provides reliable and valid measurement of QoL in a nationally representative sample. Although two structural factors were identified, the composite score is recommended for clinical decision-making. National norms and clinical significance benchmarks may facilitate MBC applications of the NQLS. Future research should evaluate its performance across additional care settings. Keywords: Quality of life, assessment, psychometrics, youth, measurement-based care, norms