[The problem of need for psychiatric facilities: problem presentations and models].

The article provides a viewpoint on the range of problems which must be met when planning institutions of psychosocial care. Definitions of needs for treatment (supplied by professionals, patients and their social environment) and characteristics of target groups (in terms of diagnosis, degree of impairment, symptoms, demographic variables, aptitude etc.) are presented. The applicability and usefulness of different epidemiological parameters and empirical approaches to estimate care requirements which have still not been fulfilled are discussed; influences on the dynamics of supply and demand are described. Planning is demonstrated as a feedback process in which the definition of participants, clarification of roles, demands and basic standards, agreement on procedures as well as implementation and evaluation are consecutive steps.