Good User Stories are INVEST

User Stories are the de-facto standard of capturing feature wishes in agile teams. The better the user stories, the better everything will work out. Even though the product owner plays a major role, honing the stories is a team effort. A good user story fulfills the INVEST criteria.

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Content of the 1-pager:

Agile teams usually capture requirements in the format “As a <role> I want <solution> so that <value>”. The whole team – business and development people together – improve stories by making them:

Independent

Independent stories can be freely re-ordered in the product backlog. Sometimes you can’t get rid of an order dependancy  but it should be an exception.

Negotiable

A user story is the reminder to have a conversation. In that conversation the team negotiates the concrete solution, the
”I want” part. The story may be enhanced or rewritten.

Valuable

Each story adds something useful for the end user / customer – the “so that” part. This leads to vertical increments: E.g. a working slice of front end, scripts & DB, instead of a finished DB without front end.

Estimable

You need a rough effort estimate to guestimate ROI and order the backlog. If you can’t estimate, you need to a) break the story into pieces or b) better understand what value it’s meant to add or c) explore unknown tech in a time-boxed research spike.

Small

Small stories are easier to estimate and test and hide fewer misunderstandings. “Small” can be 1 day in a web shop or 3 person-weeks for a medical product. At the very least, the team must be able to finish a story (“done done”) in 1 iteration.

[Problem cutting stories? See the 1-pager about Splitting Stories.]

Testable

It must be possible to write a test (at least in theory) for each story. Otherwise, how will you confirm that the story is done?
Sometimes test cases are given as acceptance criteria.
If you can’t think of a test, the story is probably to fuzzy.

Sources:

• Original article that introduced the acronym:
  http://xp123.com/articles/invest-in-good-stories-and-smart-tasks/
• http://en.wikipedia.org/wiki/INVEST_%28mnemonic%29
• http://www.agileforall.com/2009/05/new-to-agile-invest-in-good-user-stories/
• http://c2.com/cgi/wiki?InvestModelForUserStories
• http://codesqueeze.com/how-to-invest-in-your-user-stories/
• http://www.agileforall.com/2009/02/when-in-doubt-ask-how-will-i-know-ive-done-that-2/