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User stories are the de facto standard to handle requirements in an agile software development environment. They can be anything from small index cards to a few pages of text in organizations that appreciate a bit more ceremony.

Years ago, Bill Wake coined the acronym INVEST to verify if you have the right kind of user stories. He said that user stories should be

• Independent
• Negotiable
• Valuable
• Estimatable
• Small
• Testable

I just read something about the new INVEST model, which changes the meaning of Small to Sized appropriately. Mike Cohn appears to use this new definition and I saw a few references on other blogs as well.

I’m not sure I agree. A product backlog is like an iceberg: user stories on the top should be ready for inclusion in a sprint, and user stories further down the road can become Big Ugly Epics. What is so INVEST about an epic? Nothing, IMHO. You can’t negotiate an epic. You can’t estimate an epic (sure, 100 points, XXXXL or a question mark will always do). You can’t test an epic. It might be independent and the product owner can probably put some business value on it. But that’s about it.

Instead, we should relate the definition of INVEST to the ranking of the user story in the backlog. For all stories that are ready for sprint inclusion, each story should conform to INVEST. No excuses. For stories further down the backlog, INVEST can be more loosely applied. As stories rise the backlog, they should become more and more INVEST until they are ready for a sprint.

I think that this distinction is better than watering down the definition of INVEST.

Technorati: INVEST, Scrum, user stories, product backlog

Tags: Scrum //