What predicts within-person variance in applied psychology constructs? An empirical examination

The attention paid to intraindividual phenomena in applied psychology has rapidly increased during the last two decades. However, the design characteristics of studies using daily experience sampling methods and the proportion of within-person variance in the measures employed in these studies vary substantially. This raises a critical question yet to be addressed: are differences in the proportion of variance attributable to withinversus between-person factors dependent on construct-, measure-, design-, and/or sample-related characteristics? A multilevel analysis based on 1,051,808 within-person observations reported in 222 intraindividual empirical studies indicated that decisions about what to study (construct type), how to study it (measurement and design characteristics), and from whom to obtain the data (sample characteristics) predicted the proportion of variance attributable to within-person factors. We conclude with implications and recommendations for those conducting and reviewing applied intraindividual research.