Modeling Intensive Longitudinal Data

The behaviors, thoughts, and feelings related to psychopathology are often not of a static nature, but rather change and fluctuate over time in response to changes in daily life situations. Therefore, clinical psychology research can benefit from focusing on how psychopathological features behave over time, as this can provide new perspectives and insights concerning the phenomenology and mechanisms underlying psychopathology. The collection of intensive longitudinal data, consisting of many repeated measurements from single participants, allows for the investigation of several dynamic properties of single or multiple symptoms (and their interrelations). This chapter presents an overview of some major dynamic properties that can be studied with intensive longitudinal data. First, it focuses on several univariate approaches, allowing the examination of one single feature over time. Then it discusses some methods and models to further examine the dynamic relationships between two or more symptoms. For each approach, information is provided on how to calculate simple indices on a more descriptive level, as well as how to model the dynamic features using more complex models.