Defining Requirement Types: Traditional vs. Use Cases vs. User Stories

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I’ve worked with a lot of teams transitioning to agile. In each situation, user stories always seem to be a sticking point, with a common question being, “What are the differences between traditional requirements, use cases, and user stories?” I’d like to answer this question with a description and example of each requirement type. I’ll also use a running example: Imagine that we’re writing software for placement firms, and one of the firms has requested the ability to search for candidates for a specific role by specialty within a geographic location. For example, “I want to find all business analysts who are Sarbanes Oxley (SOX) experts within fifty miles of New York City.”

ChoiceTraditional Requirements
Traditional requirements are usually thought of as capabilities and constraints of the system; the key term being system. All good requirements describe what the system can do or shouldn’t do, but those requirements that focus intensely on the system tend to deemphasize user interaction or business context related to the user or business. To be fair, many traditional requirements do provide context for business and users, but that is usually not the main focus of the requirement, rather it’s the system that is the focus.

The difficulty with having the system be the focus is that it’s easy to make assumptions about what the user wants.  I’ve seen requirements be the source of record for the system’s operation.  In such a case, interacting with the business or the user while the system is being developed reverted to a series of painful, negotiated change request. The work became a matter of giving the user exactly what she asked for, which may not at all be what she needed.

This is what really makes traditional requirements tough: They’re written from the system perspective. Additionally, they’re often written in the context of a process that enforces change control and a contract based on the requirements themselves. Throw in an ideology that encourages written communication between the business analyst and the development team, and you’ve got a tough job ahead when it comes to delivering value.  Changes become a series of tightly controlled negotiations.

According to the International Institute of Business Analysts (IIBA), good requirements can be described via these criteria:

  • Requirements are complete. They must be as complete as possible with no open-ended parts or opportunity for interpretation.
  • Requirements are testable. One must be able to create a test or some sort of proof that the requirement has been met.
  • Requirements must be consistent with each other with no conflicts between what they are specifying.
  • Requirements must be design-free. Software requirements should be specified in what the system must or must not do, but not in how the software will ensure the requirement is met; that’s design.
  • Requirements must be unambiguous. No wishy-washy statements nor (conceptually) anything that can be interpreted differently than intended.

As you can imagine, good traditional requirements are tough to write and are a rare commodity. If creating a good requirement is tough, writing an entire body of requirements into a complete and locked-down specification of the system is even tougher. The level of detail can lead to many interdependencies between requirements that have to be analyzed as the requirements are developed. While all requirements specifications have this difficulty, traditional requirements are particularly touchy since the focus is on the system rather than any user interaction.

The user understandably concentrates on the interface and his interaction with the system. A simple change in the user interface can create a ripple effect through the requirements. Unless a good requirements trace is available, even small

User Comments

25 comments
Wilfried van Hulzen's picture

In my experience User Stories are very good for capturing high level requirements, expectation or business/user level goals, for the system. When necesary, which depends on the development approach, these can be detailed into system requirments and/or use cases.
This detailing should not be limited to hierarchy - a requirement or use case may contribute to several user stories.
And while user stories may overlap in subgoals or implied functionality (which follows from shared reqiurements or use cases), they should remain consistent.
Any built-in imprecision to me is not meant to encourage communication but is intended to avoid overspecification at an early stage or at business/user level. Whether to resolve that imprecision through detailed requirements determined by communication or through communication in an Agile setting depends on the process.

Finally, while face-to-face communication may be the most efficient method for conveying information, I hesitate to qualify it as the most effective. For that some record of the conversation topic as starting point and record of conversation outcome would be required, where the format of that record may be a user story, requirement, use case, mock-up/prototype, or other capture of the goal or need for the system.

September 3, 2012 - 6:35am
Wilfried van Hulzen's picture

In my experience User Stories are very good for capturing high level requirements, expectation or business/user level goals, for the system. When necesary, which depends on the development approach, these can be detailed into system requirments and/or use cases.
This detailing should not be limited to hierarchy - a requirement or use case may contribute to several user stories.
And while user stories may overlap in subgoals or implied functionality (which follows from shared reqiurements or use cases), they should remain consistent.
Any built-in imprecision to me is not meant to encourage communication but is intended to avoid overspecification at an early stage or at business/user level. Whether to resolve that imprecision through detailed requirements determined by communication or through communication in an Agile setting depends on the process.

Finally, while face-to-face communication may be the most efficient method for conveying information, I hesitate to qualify it as the most effective. For that some record of the conversation topic as starting point and record of conversation outcome would be required, where the format of that record may be a user story, requirement, use case, mock-up/prototype, or other capture of the goal or need for the system.

September 3, 2012 - 6:35am
Wilfried van Hulzen's picture

In my experience User Stories are very good for capturing high level requirements, expectation or business/user level goals, for the system. When necesary, which depends on the development approach, these can be detailed into system requirments and/or use cases.
This detailing should not be limited to hierarchy - a requirement or use case may contribute to several user stories.
And while user stories may overlap in subgoals or implied functionality (which follows from shared reqiurements or use cases), they should remain consistent.
Any built-in imprecision to me is not meant to encourage communication but is intended to avoid overspecification at an early stage or at business/user level. Whether to resolve that imprecision through detailed requirements determined by communication or through communication in an Agile setting depends on the process.

Finally, while face-to-face communication may be the most efficient method for conveying information, I hesitate to qualify it as the most effective. For that some record of the conversation topic as starting point and record of conversation outcome would be required, where the format of that record may be a user story, requirement, use case, mock-up/prototype, or other capture of the goal or need for the system.

September 3, 2012 - 6:35am
Wilfried van Hulzen's picture

In my experience User Stories are very good for capturing high level requirements, expectation or business/user level goals, for the system. When necesary, which depends on the development approach, these can be detailed into system requirments and/or use cases.
This detailing should not be limited to hierarchy - a requirement or use case may contribute to several user stories.
And while user stories may overlap in subgoals or implied functionality (which follows from shared reqiurements or use cases), they should remain consistent.
Any built-in imprecision to me is not meant to encourage communication but is intended to avoid overspecification at an early stage or at business/user level. Whether to resolve that imprecision through detailed requirements determined by communication or through communication in an Agile setting depends on the process.

Finally, while face-to-face communication may be the most efficient method for conveying information, I hesitate to qualify it as the most effective. For that some record of the conversation topic as starting point and record of conversation outcome would be required, where the format of that record may be a user story, requirement, use case, mock-up/prototype, or other capture of the goal or need for the system.

September 3, 2012 - 6:35am
Madhava Verma Dantuluri's picture

Good share. New age process of defining the use cases and implementation process.

March 2, 2014 - 11:56am

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About the author

Charles Suscheck's picture Charles Suscheck

Dr. Charles Suscheck is a nationally recognized agile leader who specializes in agile software development adoption at the enterprise level. He is one of only 11 trainers worldwide and 3 in the US certified to teach the entire Scrum.org cirriculum.  With over 25 years of professional experience, Dr. Suscheck has held positions of Process Architect, Director of Research, Principle Consultant, Professor, and Professional Trainer at some of the most recognized companies in America. He has spoken at national and international conferences such as Agile 200X, OOPSLA, and ECOOP on topics related to agile project management and is a frequent author in industry and academia. Dr. Suscheck has over 30 publications to his credit.

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