Assessing mood in daily life - Structural validity, sensitivity to change, and reliability of a short-scale to measure three basic dimensions of mood

The repeated measurement of moods in everyday life, as is common in ambulatory monitoring, requires parsimonious scales, which may challenge the reliability of the measures. The current paper evaluates the factor structure, the reliability, and the sensitivity to change of a six-item mood scale designed for momentary assessment in daily life. We analyzed data from 187 participants who reported their current mood four times per day during seven consecutive days using a multilevel approach. The results suggest that the proposed three factors Calmness, Valence, and Energetic arousal are appropriate to assess fluctuations within persons over time. However, calmness and valence are not distinguishable at the between-person level. Furthermore, the analyses showed that two-item scales provide measures that are reliable at the different levels and highly sensitive to change.