In this multi-part post, I’m going to share my personal experiences while working with user stories for gathering, tracking and planning requirements. It currently consists out of three parts:
- What are they and why do you need them?
- Who writes them and how do you control scope?
- Where do you start and what about the planning?
You can also download all parts as one comprehensive PDF for easy printing or e-reading.
Where do you start?
Suppose that after intensive discussions and tough scoping sessions you ended up with a list of user stories and are about to start building the system. The first story not only needs to realize some particular feature, but also involves building a skeleton implementation of the system’s architecture. How do you avoid spending way too much time on plumbing and other general purpose stuff you need for the rest of the stories?
The article Managing the Bootstrap Story by Jennitta Andrea addressed this challenge in more detail and offers some alternative solutions. One of these solutions is to find and define a user story with the product owner that offers minimal functionality yet still has project value. Such a story is often referred to as the backbone story because you realize the backbone of your system in it. It’s quite common to use the backbone story to realize a proof-of-concept (PoC) that verifies the chosen architecture. Since a working PoC can give the product owner confidence that the team is able to build such a product, that fact alone may be enough project value for the product owner.
You might have suspected it already, but that backbone story is just an example of another storyotype. In fact, after I started looking for an approach to capture the non-functional requirements of a project or system, I ran into a slide deck that mentioned a whole set of additional storyotypes. Dan Rawsthorne, the author, tried to define a storyotype for virtually every possible thing you might need to do in a project. Personally I think he went a bit too far, but a small set of additional storyotypes proved to be very useful anyway.
A composite user story that groups a number of stories in a logical sense.
A user story whose content and impact must be determined later in the project, but for which it is clear that it involves a significant amount of work.
A story that is used to setup the project environment, including a source control environment, a project website, a build server.
A story that involves making a technical improvement or adjustment. Examples include introducing a coding standard, refactoring a poor design, executing a performance test.
A story for writing a user manual, installation manual, etc.
A story for developing and/or hosting a training, or having a workshop with end users.
A story which objective is to fix a collection of related bugs, or spent a fixed amount of time to improve the quality of the code base.
A story that aims to do a technical investigation to determine the usability of a specific technology, or for trying an alternative technical solution.
When is the story complete?
So how do you know that a user story has been successfully realized? Well, if all is good, all stories will conform with INVEST and are associated with a number of acceptance criteria (typically written down as the how-to demo) specified by the product owner. That should be enough to determine if it is functionally sound. But what you still miss is a way of explaining the stakeholders, including the product owner, when the team treats the story as finished. That may differ by team, but usually includes some or more of the following criteria.
- The code compiles and there are no warnings or errors.
- The code meets the coding standards setup by the project or the organization.
- The code is reviewed by a peer developer.
- All automated unit and integration tests have completed successfully.
- Visual Studio’s static code analysis tool does not report any violations.
- ReSharper reports no potential errors (a.k.a. everything is 'green').
- The daily integration build has completed successfully.
- The functionality was tested by another member of the team (anybody but the developer).
- The feature or functionality has been signed off using the project checklist.
- The system functionality is tested by a tester.
- The visual look and feel is has been approved by an employee of the communications department.
Together with the story’s how-to demo these criteria are commonly referred to as the definition-of-done. Usually, a team or project will have a default definition-of-done that applies to all stories and only mentions the particulars of that story if necessary.
Then what about the planning?
User stories are an excellent unit for tracking progress within your project. However, purists within the Agile community will tell you that an Agile project will have no long term plan. Instead, the functionality is realized iteratively according to the priority defined by the product owner. I agree with the latter and believe that its iterative nature is essential for dealing with the changing requirements that are common in all projects. It allows deferring decisions to the last responsible moment, and that’s always a good thing. But in reality you often can’t escape from providing at least a rough schedule to your management. How should you deal with that?
What I often do to get all stakeholders to join me in a number of workshops. Using use case diagrams to illustrate the context of the discussions, I try to get enough stories on paper to represent the entire scope of the project. You need to beware though that you don’t write down too much details or have too much in-depth discussions. That would give the stakeholders a false sense of precision, and consequently, will cause them to see the stories as a formal functional design. Also, if you run into some high-level chunk of functionality for which nobody really knows what it will look like, add an epic story for it and include a spike to elaborate on the epic later on in the project.
Then organize a number of shorter meetings with the team or, if the team hasn’t been formed yet, with a few experienced developers. Let them discuss every story one by one and then try to estimate the size of each story in so called story points. Some people from the Agile community say you should estimate using relative sizes only. In other words, a story that seems to require twice as much work as another story should also have twice as many story points. The story point as a unit does not have value. It’s the relative differences that are important.
What works for me is that every story point corresponds to the ideal day of an experienced senior software developer. In other words, one story point means that an experienced developer familiar with the chosen architecture, technology and project methodology needs to work for 8 hours without being disturbed by telephone, email, coffee breaks, or any other distractions. Mike Cohn, author of User Stories Applied, has dedicated many chapters to this estimation technique. Ideally, each story is between 1 and 8 story points, but at the beginning of the project you still may have some epics to break up.
After finishing those meetings you should have an estimate of the total size of the project. Now, in order to get from those story points to a total number of hours you need to estimate the expected productivity of the team. Mike Cohn does this by creating a table with the expected roles, their availability (to deal with part time employees), and the expected productivity compared to the ideal senior developer (as a percentage). By calculating the average productivity and multiplying it with the number of story points you’ll end up with the total number of estimated man-hours. It’s only an estimate and both the productivity can be disappointing as well as the estimate in story points may appear to be wrong. But it still gives you an initial estimate that can be used for global planning and budget discussions. Obviously it is important to ensure that you keep on continuously measuring the actual productivity.
Wow, now what?
By now, it should be clear that a user story is not an independent concept but something that closely resonates with many of the aspects of our work in the software industry. In this multi-part post I have tried to explain a number of those aspects and to clarify the relationship between them. But even though I’ve not touched everything as detailed as possible, I still hope I've managed to convince you about the power and potential of user stories. Last but not least, if you have any questions or comments, please do not hesitate to email me at firstname.lastname@example.org or tweet me at my Twitter ID ddoomen.