title: Unsupervised Classification During Time-Series Model Building.
abstract: Researchers who collect multivariate time-series data across individuals must decide whether to model the dynamic processes at the individual level or at the group level. A recent innovation, group iterative multiple model estimation (GIMME), offers one solution to this dichotomy by identifying group-level time-series models in a data-driven manner while also reliably recovering individual-level patterns of dynamic effects. GIMME is unique in that it does not assume homogeneity in processes across individuals in terms of the patterns or weights of temporal effects. However, it can be difficult to make inferences from the nuances in varied individual-level patterns. The present article introduces an algorithm that arrives at subgroups of individuals that have similar dynamic models. Importantly, the researcher does not need to decide the number of subgroups. The final models contain reliable group-, subgroup-, and individual-level patterns that enable generalizable inferences, subgroups of individuals with shared model features, and individual-level patterns and estimates. We show that integrating community detection into the GIMME algorithm improves upon current standards in two important ways: (1) providing reliable classification and (2) increasing the reliability in the recovery of individual-level effects. We demonstrate this method on functional MRI from a sample of former American football players.
authors.affiliation: a University of North Carolina , Chapel Hill.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Gates
authors.affiliation: a University of North Carolina , Chapel Hill.
authors.forename: Stephanie T
authors.initials: ST
authors.lastname: Lane
authors.affiliation: a University of North Carolina , Chapel Hill.
authors.forename: E
authors.initials: E
authors.lastname: Varangis
authors.affiliation: a University of North Carolina , Chapel Hill.
authors.forename: K
authors.initials: K
authors.lastname: Giovanello
authors.affiliation: a University of North Carolina , Chapel Hill.
authors.forename: K
authors.initials: K
authors.lastname: Guskiewicz
mesh_terms: D000465:Algorithms; D056352:Athletes; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D001924:Brain Concussion / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D001931:Brain Mapping; D016000:Cluster Analysis; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D005538:Football / Q000293:injuries / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D015233:Models, Statistical; D009010:Monte Carlo Method; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D012306:Risk; D013997:Time Factors; D014481:United States
keywords: SEM; clustering; fMRI; intensive longitudinal; time series analysis