The Short Mood and Feelings Questionnaire from adolescence to emerging adulthood: Measurement invariance across time and sex.

Adolescence to emerging adulthood is a critical period for the onset of depressive symptoms. Understanding symptom change during this period is thus of great clinical relevance. This understanding is, however, based on the premise of the accurate measurement of depressive symptoms across time and sex, typically untested in applied research. The present study investigated longitudinal and sex measurement invariance (MI) of the Short Mood and Feelings Questionnaire (SMFQ), a widely used unidimensional 13-item measure of self-reported depressive symptoms. We employed 10 waves of the Avon Longitudinal Study of Parents and Children, a population-based study in South-West England ( N = 7,364; ages 11-26). The SMFQ exhibited increasing consistency with age: Scalar longitudinal MI was not supported by all indices in models that included ages 11 and 13, but strict MI was established from ages 14-26. At each wave, at least partial strict MI across sex was established. Sum score models with equal weightings had acceptable fit, and good reliability which was equivalent to reliability using differential weightings. External validity for sum scores was also comparable to factor scores. Thus, sum scores seem an appropriate, practical choice in many settings. Overall, findings support the use of SMFQ in assessing change in depressive symptoms from adolescence into emerging adulthood, specifically ages 14-26. Some caution is necessary when comparing the construct at ages 11-13 with ages greater than 17, when measurement models were not fully invariant. This research informs epidemiological and clinical studies on the applicability of the SMFQ across time and sex. (PsycInfo Database Record (c) 2023 APA, all rights reserved).