The proposal aims to determine the feasibility of a sophisticated system for retrieving statistical data about risk and prognosis, as a means of aiding decisions for physicians whose practice include breast-cancer patients. The proposed research will use survey methodology---including surveys of physicians and medical schools---to determine practicing physician's statistical environment, including their training, their perceived need for and attitudes about statistical data, and their use of computers and computerized databases. A set of statistical training modules will also be used to assess physicians' statistical experience. The data analysis will characterize the responding population and will identify potential barriers to physicians' use of computerized data retrieval and decision systems. These data will be used to develop guidelines for the user interface of such systems, with particular emphasis on compensating for the identified barriers. An on-line 'help' system, providing reviews of basic concepts and targeting likely errors of interpretation (for which the statistical modules will be a prototype) is viewed as a potentially important component of the interface.