INVEST Criteria - How do you know a user story is ready for estimation?

The INVEST mnemonic is a widely used checklist for assessing if a user story is well-formed and ready for the team. While often discussed in backlog refinement, its principles directly impact the sanity of estimation. Let's break it down from a practical angle:

• Independent: Minimizes dependencies, allowing for smoother planning and less blocking. Crucial for realistic sprint forecasts.
• Negotiable: Confirms the story is a conversation starter, not a rigid spec. Allows exploring better technical solutions.
• Valuable: Ensures the story delivers actual end-user value, not just internal technical tasks. Helps prioritize effectively.
• Estimable: Can the team actually put a size on this? If the story is too vague or lacks info, the answer is no, and estimation is pointless. This is a key gatekeeper.
• Small: Can it be completed within an iteration? Large stories are notoriously hard to estimate accurately and disrupt flow. Breaking them down is essential.
• Testable: Are there clear ways to verify it's done (linking back to good ACs)? Untestable stories are risky and hard to sign off on.

Use these questions to verify your story meets INVEST criteria before estimation:

• Can this story be developed without waiting for other stories, or are there dependencies?
• Is there room for technical discussion on implementation approaches, or are the requirements too rigid?
• Is the business value clearly stated in the "so that" portion, and can stakeholders validate this?
• Does the team have enough context to size this story, or are there missing details?
• Can this be completed within one sprint, or does it need breaking down?
• Are acceptance criteria clearly defined, so that we can verify when the story is complete through unit tests or test scripts?