Capturing Intraindividual Variation and Covariation Constructs: Using Multiple Time-Scales to Assess Construct Reliability and Construct Stability

The growing empirical base of studies on intraindividual variability speaks to its increasing importance in understanding human development. Studying intraindividual variability by definition requires multiple measurement occasions (e.g., microlongitudinal assessment). Tracking how intraindividual variability changes over time requires that the microlongitudinal assessment protocol be conducted again at a later time. Extended microlongitudinal studies (e.g., 100+ occasions) provide unique opportunities to study how intraindividual variability changes over time (e.g., across months). In this study the authors parse data from the 100-day Personal Understanding of Life and Social Experiences (PULSE) Project into a multiple time-scale design (four 25-day time segments) to examine the measurement reliability and stability of a variety of intraindividual variation/covariation-based constructs. Results showed that (1) reliability and stability differ across intraindividual variability constructs; (2) lability was more state-like for optimism, and trait-like for affect and goal progress; (3) intraindividual covariation-based constructs are difficult to measure reliably; and (4) in some situations it is possible to track month-to-month change in intraindividual variability using multiple burst study designs. The authors conclude that extended microlongitudinal studies be further considered as multiple time-scale designs that can, when appropriately invoked, be used to measure intraindividual variability constructs and how they change over time.