The Effect of Different Construct Operationalizations, Study Duration, and Preprocessing Choices on Power-Based Sample Size Recommendations in Intensive Longitudinal Research.

To shed light on the dynamics of psychological processes, researchers often collect intensive longitudinal (IL) data by asking people to repeatedly report on their momentary experiences in daily life. Two important decisions when designing an IL study concern the number of persons and the number of measurement occasions to be included. These sample size decisions are ideally based on statistical power considerations.

A new sample-size planning approach for person-specific VAR(1) studies: Predictive accuracy analysis.

Researchers increasingly study short-term dynamic processes that evolve within single individuals using N = 1 studies. The processes of interest are typically captured by fitting a VAR(1) model to the resulting data. A crucial question is how to perform sample-size planning and thus decide on the number of measurement occasions that are needed.