title: Modeling contextual effects using individual-level data and without aggregation: an illustration of multilevel factor analysis (MLFA) with collective efficacy.
abstract: Population health scientists increasingly study how contextual-level attributes affect individual health. A major challenge in this domain relates to measurement, i.e., how best to measure and create variables that capture characteristics of individuals and their embedded contexts. This paper presents an illustration of multilevel factor analysis (MLFA), an analytic method that enables researchers to model contextual effects using individual-level data without using derived variables. MLFA uses the shared variance in sets of observed items among individuals within the same context to estimate a measurement model for latent constructs; it does this by decomposing the total sample variance-covariance matrix into within-group (e.g., individual-level) and between-group (e.g., contextual-level) matrices and simultaneously modeling distinct latent factor structures at each level. We illustrate the MLFA method using items capturing collective efficacy, which were self-reported by 2,599 adults in 65 census tracts from the Los Angeles Family and Neighborhood Survey (LAFANS). MLFA identified two latent factors at the individual level and one factor at the neighborhood level. Indicators of collective efficacy performed differently at each level. The ability of MLFA to identify different latent factor structures at each level underscores the utility of this analytic tool to model and identify attributes of contexts relevant to health.
authors.affiliation: Psychiatric and Neurodevelopmental Genetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, 185 Cambridge Street, Simches, Room 6.252, Boston, MA 02114 USA.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Dunn
authors.affiliation: Division of Epidemiology and Biostatistics, School of Public Health, Georgia State University, Atlanta, GA 30302 USA.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Masyn
authors.affiliation: Harvard Graduate School of Education, 6 Appian Way, Cambridge, MA 02138 USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Johnston
authors.affiliation: Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Kresge Building 7th Floor, 716, Boston, Massachusetts 02115 USA.
authors.forename: S V
authors.initials: SV
authors.lastname: Subramanian
keywords: Collective efficacy; Context; Ecological; Environment; Factor analysis; Latent variable; Multilevel; Neighborhood