The purpose of the project is to provide an exploratory investigation of a variety of factors which are thought to be related to the impact of measurable patient flows in the specification and interpretation of the acute hospital service area. In particular, emphasis is directed at the importance of designation of hospital service areas using empirical rather than normative approaches; of consideration of selected hospital/patient, physician/hospital, and physician/patient relationships as major intervening variables in the specification of hospital service area patterns (including patterns of patient flow both within and out of derived hospital service areas); and finally, of modifications which may be used in the specification of hospital service areas (based on study findings) which may make for better use of the hospital service area as an analytical unit for certain health planning objectives. Specifically, the following areas of consideration will be addressed: 1) The history, importance and different methods for identifying hospital service areas for hospital and health planning; 2) Problems, limitations and weaknesses of current hospital service area approaches, including implicit and explicit assumptions; 3) The relationship of the patient to physician to hospital flow on hospital service area patterns; 4) Identification of approaches for better understanding of the hospital service area; 5) Impact of identified approaches on uses of the hospital service area for hospital and health planning. The test site area under investigation will be the State of Rhode Island. All data collection and required information will be accessed through R.I. Health Services Research, Inc. (SEARCH). The data files to be used are: The Uniform Hospital Discharge Data Set, The Health Facilities Data File, The Health Manpower Data File, and The R.I. Health Interview Survey. The analytical methods will include derivation of two measures of patient flow: resident dependency and hospital dependency for specification of service areas. The service area patient out-flow will be the dependent variable for which several patient/physician and physician/hospital characteristics (independent variables) will be tested for possible correlation. The results of the investigation are intended to be useful in terms of better understanding and application of hospital service area as a basic analytical unit for health planning.