Users, programmers, and statistical software

Statistical software provides essential support for statisticians and others who are analyzing data or doing research on new statistical techniques. Those supported typically regard themselves as "users" of the software, but as soon as they need to express their own ideas computationally, they in fact become "programmers." Nothing is more important for the success of statistical software than enabling this transition from user to programmer, and on to gradually more ambitious software design. What does the user need? How can the design of statistical software help? This article presents a number of suggestions based on past experience and current research. The evolution of the S system reflects some of these opinions. Work on the Omegahat software provides a promising direction for future systems that reflect similar motivations.