Clinicaltrials.gov, NCT02754895.

Background: Optimism, or positive expectations about the future, is associated with better health. It is commonly assessed as a trait, but it may change over time and circumstance. Accordingly, we developed a measure of state optimism. Methods: An initial 29-item pool was generated based on literature reviews and expert consultations. It was administered to three samples: sample 1 was a general healthy population (n=136), sample 2 was people with cardiac disease (n=96), and sample 3 was persons recovering from problematic substance use (n=265). Exploratory factor analysis and item-level descriptive statistics were used to select items to form a unidimensional state optimism measure (SOM). Confirmatory factor analysis (CFA) was performed to test fit. Results: The selected seven SOM items demonstrated acceptable to high factor loadings on a single dominant factor (loadings: .64-.93). There was high internal reliability across samples (Cronbach's alphas: .92-.96), and strong convergent validity correlations in hypothesized directions. The SOM's correlations with other optimism measures indicate preliminary construct validity. CFA statistics indicated acceptable fit of the SOM model. Conclusions: We developed a psychometrically-sound measure of state optimism that can be used in various settings. Predictive and criterion validity will be tested in future studies.