Are we on the same page? Latent variable modeling suggests different nomothetic and idiographic factor structures for momentary affect

Objective: This study investigated the factor structure underlying affect and whether it differs within and between persons. Method: In an exploratory study, 12 datasets of self-reported momentary emotions collected via experience sampling method (11 datasets) and daily diaries (one dataset) were analyzed using graded response models based on item response theory. Before doing so, two pools of datasets were extracted so that the intraindividual (sampling all measurements of a person) and interindividual (sampling measurement occasions of different individuals) variations are disentangled. Various factor models were then fitted to each pool via an alternative-model confirmatory factor analysis. The candidate models were compared according to their relative goodness of fit. The best-fitting models were defined using a vote-counting method. Results: The intrapersonal momentary variations of affect can be best explained by a unidimensional factor structure resembling valence while individual differences are explained by a two-dimensional construct similar to positive and negative activation constructs. Conclusions: The structure of change in affect is not the same between and within persons. This implies that the nomothetic and idiographic analyses do not converge, providing evidence for construct nonequivalence between the two levels of analysis.