Capturing Schizophrenia Symptoms in Daily Life via the Smartphone: Psychometric Evaluation of Newly Developed Symptom Scales

<p>Schizophrenia (SCZ) is a severe mental health condition and a leading contributor to disability. Ecological momentary assessment (EMA) offers an approach for capturing symptoms in daily life while reducing recall bias, yet validated EMA instruments for SCZ remain limited. Here, we developed and evaluated an EMA scale assessing positive, negative, and cognitive symptoms in individuals with SCZ (N = 83) using data from Sensing Schizophrenia. Participants had a mean age of 40.11 years, 50.0% identified as female, and 76.8% as White. Internal consistency was assessed using generalizability theory, Nezlek’s framework, and omega coefficients and validity was assessed using correlation analyses. Between-person reliability was consistently strong (ω ≥ 0.86; GT/Nezlek ≥ 0.997), indicating stable measurement of individual differences. Positive symptoms showed lower and more variable within-person reliability (GT = 0.63, Nezlek = 0.18, ω = 0.63), while negative and cognitive symptoms showed moderate and more consistent estimates (negative: 0.68-0.78; cognitive: 0.5-0.69), suggesting that the positive symptom subscale may require further research. Convergent validity showed moderate to strong associations with established retrospective measures for positive and negative symptoms at weekly and post-assessment (ρ = 0.40–0.65), supporting validity for these domains. Convergent validity for cognitive symptoms could not be assessed due to the absence of comparable measures. Across extended aggregation windows (7–90 days), associations to the post assessment remained stable, indicating robust correspondence between EMA and retrospective reports. Overall, findings support the reliability and validity of the developed EMA scale for SCZ symptoms.</p>