That product requirements are unstable is a fact known to practitioners and well documented in academic literature.
One of the authors has worked with hundreds of product developers and has yet to find a single project in which the requirements remained stable throughout the design. Surveying more than 200 product developers over the past five years, he found that fewer than 5% had a complete specification before beginning product design. On average, only 58% of requirements were specified before design activities began. The inevitable result is changes.
Academic research in the area of technological innovation has shown that a significant part of these changes can be attributed to:
- the co-evolution of technical solutions in components that are pan of a larger system;
- customers' inherent difficulty in accurately specifying their needs at the outset of a design project system.
From the California Management Review