Second, this study also draws attention to the utility of a person-oriented approach (Bergman & Magnusson, 1997; von Eye & Bergman, 2003) for evaluation research, and of the integrative strategy between person-oriented and variable-oriented approaches (Bates, 2000) to clinical research more broadly. As Foster, Dodge, and Jones (2003) recently discussed, many prevention and treatment studies are conducted from a variable-oriented perspective. Foster and colleagues illustrated that while studies utilizing a variable-oriented approach allow one to measure cost-effectiveness per one unit improvement in a single outcome measure, it is difficult to answer whether the cost of interventions outweighs benefits when the emphasis lies not on persons, but on variables. It is especially challenging when outcomes co-occur. Foster and colleagues, therefore, suggested that a person-oriented outcome may be used as a global measure of cost-effectiveness for prevention research. Identifying heterogeneous subgroups based on two related outcome measures (e.g., AP and HED) may be more insightful than those from an isolated single outcome when assessing clinical significance at the individual level or global cost-effectiveness. Recent advances in longitudinal research methodology (see Foster &
