INVEST
Updated 2026-08-09
INTRODUCTION
English translation pending.
CORE DEFINITION
INVEST is a set of six criteria for evaluating user stories, associated with Bill Wake and widely used in agile practice. A good story is Independent, so it can be scheduled without depending on another story. It is Negotiable, meaning it records an intent to be discussed rather than a fixed contract. It is Valuable, delivering something the customer or user actually wants. It is Estimable, so the team can size it. It is Small, fitting comfortably within a single iteration. It is Testable, with criteria that let the team verify completion. The criteria assume requirement quality can be judged before development begins.
SCAFFOLDING EFFECT
Reduce cognitive load
- Use story gate: run each candidate story through the six criteria before it enters an iteration. - Use split trigger: when a story fails estimable or small, split it rather than accepting the ambiguity. - Use testability check: write acceptance criteria and reject stories that cannot be verified.
Anchor fast decisions
Large ambiguous requirements enter backlogs because nobody can tell they are unusable until work starts. Applying the six criteria at intake surfaces the failure early, when splitting is cheap. Independence and smallness limit the coupling that makes estimates unreliable, and testability forces the requirement to be stated precisely enough to verify. Estimability acts as a diagnostic: if a team cannot size a story, the cause is usually missing information or excessive scope, and both are fixed by reworking the story rather than by estimating harder.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/INVEST_(mnemonicverified
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