Page 16 - Age of onset of disruptive behavior of residentially treated adolescents -Sjoukje de Boer
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some extent by using multi-informant information and not solely relying on (subjective) recall of events, but also on reliable, objective, established occurrences of events. Because retrospective findings may not be as reliable as prospective findings, it cannot be excluded however that the inherent limitations in the operationalization of the retrospective (EO and AO) and the prospective (LCP and AL) group differentiations have influenced the results of this thesis.
Moreover, even if it were possible to assess age of onset reliably, it would still be complicated to compare with other studies, since studies on age of onset often differ in the operationalization of key concepts. Disruptive or antisocial behavior itself in particular, is heterogeneous. There are several ways in which such behavior can be described, for instance by including delinquent, aggressive or violent, externalizing or rule breaking behavior. These concepts partially overlap, while not being completely similar. At present, different operationalizations are used in different studies. Sanford and colleagues (1999) for instance used the age of the first conduct disorder symptom, while others required an actual diagnosis of CD and/or ODD (e.g., Kolko et al., 2009; Webster-Stratton et al., 2004), suspension records (e.g., Houghton et al., 2017), conviction records or arrest records (e.g., Dean, Brame, & Piquero, 1996; Patterson & Yoerger, 1997; Piquero, Daigle, Gibson, Leeper-Piquero, & Tibbetts, 2007) or the self reported (e.g., Dandreaux & Frick, 2009) or official age of the first offence (e.g., Carroll et al., 2006; Tibbetts & Piquero, 1999). While these groups overlap substantially, differences are noteworthy. In specific, not all juvenile delinquents fulfill the characteristics of conduct disorder, while conversely, not all juveniles with a conduct disorder will be involved in crimes which will lead them into criminal law. In the present thesis, the classification of Frick was used for the operationalization of disruptive behavior. Frick and colleagues (1993) conducted a meta-analysis, that resulted in a classification in which all types of disruptive behaviors were contained, covering an overt/covert dimension, as well as a destructive/non-destructive dimension. The term disruptive behavior encapsulated antisocial behavior (i.e., status offences, and property violations), oppositional behavior and aggressive behavior, and roughly corresponds with the behaviors covered by disruptive behavior disorders as used in the DSM-IV (American Psychiatric Association, 1994; APA, 2000).
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