: Briand, L.C.; Bunse, C.; Daly, J.; Differding, C.

Abstract
This paper presents a controlled experiment focusing on the following issues (i) are object-oriented design documents easier to understand and modify than structured design documents?, (ii) must they comply with quality design principles such as the ones provided by Coad and Yourdon?, and (iii) what is the impact of such design principles on the understandability and modifiability of design documents? Results strongly suggest that such design principles have a beneficial effect on the maintainability of object-oriented design documents. However, there is no strong evidence regarding the alleged higher maintainability of object-oriented design documents over structured design documents. Furthermore, results suggest that object-oriented design documents are more sensitive to poor design practices, in part because their cognitive complexity becomes increasingly unmanageable. However, as our ability to generalise these results is limited, they should be considered as preliminary, i.e., it is very likely that they can only be generalised to programmers with little object-oriented training. Such programmers can, however, be commonly found on maintenance projects.