As a consequence of these studies Guindon developed an understanding of design and development work as it unfolds over time; it is in vact a chaotic process of learning and reflection through trial and error. In essence the process of creating a solution to an ill-structured problem is itself un-structured, at least in the simplistic sense of being a planned, logical process moving from high level design to low level implementation in a smooth orderly manner. In fact the observations lead Guindon to the conclusion that software design work is largely underdetermined (Guindon, 1990).
“opportunistic decomposition is better suited to handle the ill-structuredness of design problems… top-down decomposition appears to be a special case for well-structured problems when the designer already knows the correct decomposition. .” (Guindon, 1990)
Guindon’s study demonstrated empirically that top-down design doesn’t occur as such in design work, or at least it doesn’t occur in a linear sequence from top to bottom. This has implications for lifecycles and frameworks that impose linear or staged phase structures based on the concept of top-down design-to-development processes.
Reference: Guindon, R. (1990) Designing the Design Process: Exploiting Opportunistic Thoughts. Human-Computer Interaction, 5, 305-344.