This is the proceedings of the Sixth Symposium on Empirical Foundations of Information and Software Sciences (EFISS), which was held in Atlanta, Georgia, on October 19-21, 1988. The purpose of the symposia is to explore subjects and methods of scientific inquiry which are of common interest to information and software sciences, and to identify directions of research that would benefit from the mutual interaction of these two disciplines. The main theme of the sixth symposium was modeling in information and software engineering, with emphasis on methods and tools of modeling. The symposium covered topics such as models of individual and organizational users of information systems, methods of selecting appropriate types of models for a given type of users and a given type of tasks, deriving models from records of system usage, modeling system evolution, constructing user and task models for adaptive systems, and models of system architectures. This symposium was sponsored by the School of Information and Computer Science of the Georgia Institute of Technology and by the U.S. Army Institute for Research in Management Information, Communications, and Computer Sciences (AIRMICS). 17le Editors vii CONTENTS 1 I. KEYNOTE ADDRESS ............................................. .

The monograph presents the proceedings of the Third Symposium on Empir ical Foundations of Information and Software Sciences (EFISS) held at the Riso National Laboratory in Roskilde, Denmark, 23-25 October 1985. The EFISS series of meetings was initiated with the express purpose of explor ing subjects and methods of scientific inquiry of empirical nature which are of common interest to information and software sciences. Furthermore, these meetings were expected to provide a cross-disciplinary forum for discussion of problems and exchange of research results of importance for the design and application of advanced information systems. The previous two EFISS symposia took place at the Georgia Institute of Technology in Atlanta, Georgia, USA. The first meeting in 1982 focused on methods of experimental design and measurement techniques in information and software sciences. The second meeting was held in 1984 and its main theme was the value of information in prescriptive contexts, such as value of information for understanding and implementation of these messages, instructions, and commands. Specific examples of problems of this kind are the value of comments for the enhancement of understanding of computer programs, the value of information in assisting and guiding users of on line interactive systems, and the value of lexical aids in information retrieval. In both symposia, contributed papers were considered on any other valid subject of empirical foundations of the said two sciences."