INVEST Model for User Stories

The INVEST model is a guideline used in Agile development to ensure that user stories are well-written and effective. It helps product owners, Scrum masters, and development teams create user stories that are clear, testable, and valuable.

What is a User Story?

A user story is a short, simple description of a feature told from the perspective of the end user or customer. It usually follows the format:

As a [type of user],

I want [some goal]

so that [some reason].

 

INVEST Model Explained

INVEST is an acronym where each letter stands for a characteristic of a good user story:

I – Independent

User stories should be independent of each other. This allows them to be developed and delivered in any order. It reduces dependencies and enables better planning and flexibility.

N – Negotiable

A user story is not a contract. It should be negotiable and open to discussion. The details can be refined through conversations between stakeholders and the development team.

V – Valuable

Each user story must deliver value to the end user or customer. If the story doesn’t provide value, it shouldn’t be included in the backlog.

E – Estimable

The story must be clear enough to estimate the amount of effort or time required to implement it. If it’s too vague, it can’t be properly planned or prioritized.

S – Small

A user story should be small enough to complete within a single iteration or sprint. Large stories should be broken down into smaller, manageable parts.

T – Testable

There should be clear criteria to determine whether the user story is complete. A story is testable if the team can write tests (manual or automated) to verify its functionality.

Example of a Good User Story (Using INVEST)

As a registered user, I want to reset my password so that I can regain access to my account if I forget it.

This story is:

• Independent: It can be developed separately from other features.
• Negotiable: Details like the reset method (email, SMS, etc.) can be discussed.
• Valuable: Users gain the ability to access their accounts again.
• Estimable: Clear enough to estimate effort.
• Small: Can be completed in a sprint.
• Testable: Can write tests to confirm the reset functionality works.

Summary Table

INVEST Attribute	Description
I – Independent	No dependency on other stories
N – Negotiable	Can be changed or discussed
V – Valuable	Provides value to the user or customer
E – Estimable	Can be estimated by the team
S – Small	Fits within one sprint or iteration
T – Testable	Can be verified with tests

Using the INVEST model ensures that user stories are practical, focused, and contribute meaningfully to the product’s success.