ERIC Number: EJ775069
Record Type: Journal
Publication Date: 2007-Sep
Reference Count: N/A
Combining Propensity Score Matching and Group-Based Trajectory Analysis in an Observational Study
Haviland, Amelia; Nagin, Daniel S.; Rosenbaum, Paul R.
Psychological Methods, v12 n3 p247-267 Sep 2007
In a nonrandomized or observational study, propensity scores may be used to balance observed covariates and trajectory groups may be used to control baseline or pretreatment measures of outcome. The trajectory groups also aid in characterizing classes of subjects for whom no good matches are available and to define substantively interesting groups between which treatment effects may vary. These and related methods are illustrated using data from a Montreal-based study. The effects on subsequent violence of gang joining at age 14 are studied while controlling for measured characteristics of boys prior to age 14. The boys are divided into trajectory groups based on violence from ages 11 to 13. Within trajectory group, joiners are optimally matched to a variable number of controls using propensity scores, Mahalanobis distances, and a combinatorial optimization algorithm. Use of variable ratio matching results in greater efficiency than pair matching and also greater bias reduction than matching at a fixed ratio. The possible impact of failing to adjust for an important but unmeasured covariate is examined using sensitivity analysis.
Descriptors: Males, Observation, Control Groups, Matched Groups, Outcomes of Treatment, Research Methodology, Individual Characteristics, Early Adolescents, Juvenile Gangs, Violence, Behavior Problems, Behavior Patterns, Statistical Analysis, Research Problems, Foreign Countries
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Authoring Institution: N/A
Identifiers - Location: Canada (Montreal)