There has been little research on end-user program development beyond the activity of programming. Devising ways to address additional activities related to end-user program development may be critical, however, because research shows that a large proportion of the programs written by end users contain faults. Toward this end, we have been working on ways to provide formal "software engineering" methodologies to end-user programmers. This paper describes an approach we have developed for supporting assertions in end-user software, focusing on the spreadsheet paradigm. We also report the results of a controlled experiment, with 59 end-user subjects, to investigate the usefulness of this approach. Our results show that the end users were able to use the assertions to reason about their spreadsheets, and that doing so was tied to both greater correctness and greater efficiency.

Spreadsheets are among the most common form of software in use today. Unlike more traditional forms of software however, spreadsheets are created and maintained by end users with little or no programming experience. As a result, a high percentage of these "programs" contain errors. Unfortunately, software engineering research has for the most part ignored this problem. We have developed a methodology that is designed to aid end users in developing, testing, and maintaining spreadsheets. The methodology communicates testing information and information about the impact of cell changes to users in a manner that does not require an understanding of formal testing theory or the behind the scenes mechanisms. The paper presents the results of an empirical study that shows that, during maintenance, end users using our methodology were more accurate in making changes and did a significantly better job of validating their spreadsheets than end users without the methodology.