Skip to main content

Poor Definition of "Requirement"

Karl Wiegers, author of several books on product requirements, says his favorite definition of requirement is:
"Requirements are…a specification of what should be implemented. They are descriptions of how the system should behave, or of a system property or attribute. They may be a constraint on the development process of the system."
This unfortunate definition comes from Ian Sommerville and Pete Sawyer.

Frequent readers of this blog know that I find this definition to be overly broad. After all "a specification of what should be implemented" could include a detailed design specification with UML class and collaboration diagrams. Wieger's favorite definition thus fails to provide any meaningful distinction between requirements and design.

A proper definition of requirement must clearly distinguish between requirements and design.

Comments

Unknown said…
Agreed. A good requirement is a statement of the problem, that can be solved, and absent a design of how to solve it.

See my article "On Reqs and Specs" for more. http://www.pragmaticmarketing.com/publications/topics/09/on-reqs-and-specs/
Mon Mar 14, 11:14:00 AM 2011
Roger L. Cauvin said…
Thanks, Steve. Your "On Reqs and Specs" is highly recommended, and I think it hits the nail on the head. It's nice that one of the most respected authorities in the product management community has drawn attention to this issue.
Mon Mar 14, 12:25:00 PM 2011
Post a Comment

Popular posts from this blog

Why Spreadsheets Suck for Prioritizing

The Goal As a company executive, you want confidence that your product team (which includes all the people, from all departments, responsible for product success) has a sound basis for deciding which items are on the product roadmap. You also want confidence the team is prioritizing the items in a smart way. What Should We Prioritize? The items the team prioritizes could be features, user stories, epics, market problems, themes, or experiments. Melissa Perri  makes an excellent case for a " problem roadmap ", and, in general, I recommend focusing on the latter types of items. However, the topic of what types of items you should prioritize - and in what situations - is interesting and important but beyond the scope of this blog entry. A Sad but Familiar Story If there is significant controversy about priorities, then almost inevitably, a product manager or other member of the team decides to put together The Spreadsheet. I've done it. Some of the mos
32 comments
Read more

Interaction Design: the Neglected Skill

Your product development organization has a big, gaping hole in it. (Be prepared to feel defensive as you continue reading.) One of the most important roles in product development is the role of interaction designer. An interaction designer designs how the users will interact with the product and conceptualize the tasks they perform. He decides whether, for example, the user interface will be command driven, object oriented (clicking on objects then specifying what to do with them), or wizard based. The interaction designer decides the individual steps in the use cases. Every company has one or more people that play the interaction designer role. Usually, those people have little or no expertise in interaction design. Sadly, they typically don't even realize how unqualified they are. Let's see who typically plays the role at companies. Engineer . An engineer is an expert on building what is designed. Yes, an engineer may know how to design the internal structure of the hardware
8 comments
Read more