On the relation between person-oriented and subject-specific approaches

The necessity of using subject-specific data analysis of non-ergodic psychological processes is explained, emphasizing the difference between inter-individual and intra-individual variation. It is argued that subject-specific data analysis not only matches the principles underlying Developmental Systems Theory, but also enables testing of all principles of person-oriented theory. A new generalized perspective on measurement equivalence in subject-specific data analysis is introduced. The importance of computational optimal control of psychological processes within the context of subject-specific data analysis is emphasized. In closing, some broader aims of subject-specific data analysis are considered.