TL; DR
User story mapping is about describing a narrative and creating structure for conversations, not for defining a pile of requirements.
User Mapping in Detail
User story mapping is not directly about building a Product Backlog. It is about building a narrative for your product to encourage discussions about what to build, and what the minimum viable product really looks like. Specifically, you should approach user story mapping as an exercise in describing the flow of user experience rather than getting bogged down in implementation details.
Consider this excerpt:
- Stories aren’t a written form of requirements; telling stories through collaboration with words and pictures is a mechanism that builds shared understanding.
- Stories aren’t the requirements; they’re discussions about solving problems for our organization, our customers, and our users that lead to agreements on what to build.
— Jeff Patton. User Story Mapping (Kindle Locations 477-480). O’Reilly Media, Inc..
A Worked Example
Instead of focusing on features, your story map really out to strive to tell a story about the experience of using the product. For example, you might decide to tell Jane's story:
- Jane wants to buy an M1 Abrams tank from our web site.
- Jane finds the tank in the catalog.
- Jane adds the tank to her cart.
- Jane tries to check out in one of two ways:
- Jane checks out without registering.
- Jane checks out with optional registration.
- Jane creates buzz for the company when she goes on a road-rage rampage in her new tank.
- Profit!
Once you've told Jane's story in the large, you have refining conversations about what's needed to make each piece of that story a functional slice of product.
Advice on the Emergent Mapping
Don't try to build your map up from user stories. Instead, define your narrative and build your feature list down from the narrative. This is admittedly somewhat of an art, as the story map is really an emergent property of the exercise rather than a formulaic construct.
You may find yourself shuffling stories, epics, and themes a great deal in the beginning. You might also find yourself redefining your narrative several times as a result of the conversations that story mapping is intended to trigger. That's all to be expected.
Remember, the goal is to tell a story about the product. The user stories themselves will emerge as a by-product of the storytelling process.