Skip to main content

Limitations of "The system shall . . . ."

Is your product manager composing documents with hundreds of sentences beginning with "The system shall . . . ." or "The product shall . . . ."? If so, she should consider a different approach.

Back in 2004, Mike Cohn wrote an interesting article on requirements and agile development. Here is an interesting excerpt from the article:
[C]onsider the following requirements:

3.4) The product shall have a gasoline-powered engine.
3.5) The product shall have four wheels.
3.5.1) The product shall have a rubber tire mounted to each wheel.
3.6) The product shall have a steering wheel.
3.7) The product shall have a steel body.

By this point, I suppose images of an automobile are floating around your head. Of course, an automobile satisfies all of the requirements listed above. The one in your head may be a bright red convertible, while I might envision a blue pickup. Presumably the differences between your convertible and my pickup are covered in additional requirements statements.

But suppose that instead of writing an IEEE 830–style requirements specification, the customer told us her goals for the product:

* The product makes it easy and fast for me to mow my lawn.
* I am comfortable while using the product.

By looking at goals, we get a completely different view of the product: the customer really wants a riding lawnmower, not an automobile. These goals are not user stories, but where IEEE 830 documents are a list of requirements, stories describe a user’s goals. By focusing on the user’s goals for the new product, rather than a list of attributes of the new product, we can design a better solution to the user’s needs.
It's revealing that a product satisfying the first alleged "requirements" specification (the series of "The product shall . . . ." statements) likely would fail miserably at addressing the user's real needs. The real requirements are to mow the user's lawn, and for it to be fast, easy, and comfortable for the user.

Via Jonathan Babcock.

Comments

Unknown said…
Hi,

I agree with your observation, but not quite sure if that is the problem of "The System/Product shall......."

What alternative do you have in mind?
Roger L. Cauvin said…
The problem with "The system shall . . . ." is using it to document interaction design.

Requirements are user goals and nonfunctional requirements that we attach to those goals. It is fine to express requirements in terms of "The system shall . . . ."

But when we break those user goals into fleshed out use cases that detail user interactions with the system to achieve the goals, we move into interaction design. Why should we then turn around and write hundreds of "The system shall . . . ." statements to express what is already implicit in the fleshed-out use cases?
Unknown said…
This may be a little far-fetched, but have you tried not to use Use Cases, rather light wieght user stories? Do you really find value in use cases?

Rajeev
Roger L. Cauvin said…
I find tremendous value in both user stories and use cases.

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

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

Stop Validating and Start Falsifying

The product management and startup worlds are buzzing about the importance of "validation". In this entry, I'll explain how this idea originated and why it's leading organizations astray. Why Validate? In lean startup circles, you constantly hear about "validated learning" and "validating" product ideas: The assumption is that you have a great product idea and seek validation from customers before expending vast resources to build and bring it to market. Indeed, it makes sense to transcend conventional approaches to making product decisions . Intuition, sales anecdotes, feature requests from customers, backward industry thinking, and spreadsheets don't form the basis for sound product decisions. Incorporating lean startup concepts , and a more scientific approach to learning markets, is undoubtedly a sounder approach. Moreover, in larger organizations, sometimes further in the product life-cycle, everyone seems to have an opinio