Testing a Bifactor Model of Relational and Physical Aggression in Early Childhood

Different approaches have been used to classify children as relationally aggressive, physically aggressive, or both relationally and physically aggressive (co-occurring aggression). The goal of the current study (N = 164, 50.9% boys, M _age = 47.75 months, SD = 7.37) was to test a bifactor model of aggression, which allows for aggression to be assessed dimensionally, and postulates a co-occurring aggression factor as well as unique relational and physical aggression factors, during early childhood. Aggression was measured using reliable observer and teacher reports of physical and relational aggression subscales. The two-factor model was an adequate fit to the data but the bifactor model was a significant improvement in model fit compared to the two-factor model. Alternative statistics for evaluating bifactor models were used in the current study. The measurement invariance (e.g., configural invariance, metric invariance, and scalar invariance) of the bifactor model was tested across gender and results from the bifactor model using teacher report showed that the model was invariant across gender. Lastly, the criterion validity of the model was examined by evaluating the relations between the bifactor model and observations of physical and relational aggression and results generally supported the validity of the bifactor model. Overall, results suggest that a bifactor model of aggression may be a useful method for studying aggression in early childhood.