Creating clear, high-quality user stories is key to building great products with Agile development. But what makes a user story “good” can be subjective. This is where the INVEST technique comes in handy.
INVEST provides memorable criteria to assess and improve Agile user stories. It stands for Independent, Negotiable, Valuable, Estimable, Small, and Testable. Stories that meet these standards tend to be easier to understand, discuss, prioritize, estimate, implement, and test.
This guide will explain the INVEST criteria in depth using real-world examples, and how applying INVEST can help your team collaborate better, adapt to change, accelerate development, and deliver more value to users.
What is a User Story in Agile?
You probably know what a user story is but a refresher won’t hurt. A user story captures a requirement as a short, simple description of functionality told from the perspective of the person who desires the new capability in a product or system.
User stories typically follow the simple narrative format:
“As a [type of user], I want [an action] so that [a benefit/value].”
The user story embodies the value the user will obtain from the new capability or feature. It serves to place the user at the center when defining product requirements.
User stories are intentionally kept brief to facilitate discussion, refinement, and estimation. They help break down large requirements into small, testable increments that can be completed iteratively in a time-boxed Agile sprint.
Good user stories are vital to maximizing the delivery of desired outcomes and minimizing the risk of developing features the users won’t find helpful. Applying techniques like INVEST helps create effective user stories aligned with core Agile principles.
You can do some more reading of the 3C’s of user stories here.
What is INVEST in Agile?
Now let’s dive into the details of each INVEST criterion and why it matters for writing great Agile user stories.
1. Independent
Independent means the user story should be self-contained and not dependent on other stories for completion.
When stories have interdependencies, teams often cannot start or fully complete a story until its preceding dependencies are finished. This causes delays in delivering working software. It also hinders the Product Owner’s ability to prioritize the backlog based on maximum value.
Instead, user stories should represent small vertical slices of functionality that can be developed, tested, and potentially released independently:
An example of an independent user story is “As a user, I can register a new account so that I can access the app’s features.”
An example of a user story that is not independent is “As a user, I can update my account profile after registering my new account.”
The second story depends on the first one being completed to be actionable.
Of course, some logical dependencies between stories are unavoidable. However, applying INVEST encourages finding ways to separate dependencies whenever possible. For example, stubbing out service calls or using mock data to enable front-end work to proceed even if back-end stories are not finished yet.
The independent criterion promotes both faster delivery of user value and greater flexibility to respond to change, two core Agile principles. Independent stories minimize workflow bottlenecks and constraints.
2. Negotiable
The negotiable criterion emphasizes that the user story is not a detailed specification set in stone. Instead, it is a starting point for an ongoing conversation between the product owner and development team to reach alignment.
Treating stories as negotiable rather than prescriptive encourages:
- Two-way learning between business and technical perspectives
- Leveraging the team’s expertise in shaping solution options
- Adapting stories based on emerging insights and constraints
By promoting this collaborative refinement, INVEST creates a shared understanding of both the problem and possible solutions. The development team feels empowered to apply their creativity and problem-solving skills, while still satisfying the product owner’s intent.
Stories that specify detailed requirements and technical solutions tend to limit the potential for innovation and leave little room for discoveries or new alternatives to emerge through team dialogue.
3. Valuable
The valuable criterion emphasizes that every user story must clearly capture the value it will deliver if completed as described.
Some of the ways to make stories valuable include:
- Describing how it helps users complete relevant tasks or achieve goals
- Quantifying the expected business benefit
- Identifying the risks or costs it will mitigate
- Specifying how it aligns with the product vision and strategy
Requiring statements of value ensures the Product Owner deliberately considers how each story contributes to strategic outcomes and metrics. This also forces prioritization decisions to be driven by maximizing delivered value.
Stories without a clear value statement often end up vague, ambiguous, or unnecessary. They can lead to wasted effort implementing low-value Agile features or working on solutions that do not really align with product and user needs.
4. Estimable
For a story to be estimable, it must be defined clearly enough that the team can gauge the relative effort required to complete it.
Accurate effort estimation is essential for several core Agile practices:
- Sprint planning and establishing team velocity
- Prioritizing the backlog based on cost-benefit analysis
- Splitting large stories into smaller, shippable increments
- Forecasting roadmaps and release plans
To estimate a story’s size, details like these are helpful:
- Expected number of screens/components involved
- Complexity of logic/algorithms required
- Types of testing needed
- External dependencies or unknowns
Without an estimable story, Sprint planning risks becoming misaligned with actual capacity, making reliable delivery of value unpredictable.
5. Small
Small means user stories should capture the smallest possible increment of customer value.
Excessively large stories strain estimability and hinder completing work within a single Sprint. This impedes obtaining rapid feedback on whether the implemented solution actually met the user’s need.
As a rule of thumb, Agile teams aim to complete stories within one Sprint. A small user story is typically no more than a few days of development effort. Guidelines like the below can help gauge the appropriate story size:
- Fits on a small sticky note or notecard
- Requires less than ~40 hours of work
- Delivers a thin vertical slice of functionality
5. Testable
The final INVEST criterion is that a good user story must be testable, meaning that there are clear, objective criteria for determining whether the story was successfully implemented as intended.
Testable stories make it straightforward to:
- Derive specific test cases to confirm functionality
- Assess the scope of work remaining on a story mid-iteration
- Validate all acceptance criteria are fulfilled before finalizing a story
To write testable stories, include:
- Precise expected outcomes, not vague capabilities
- Metrics that can easily be measured and observed
- Assertions that must prove true when the story is complete
Well-defined acceptance criteria are essential for development teams to build effective automated checks that validate the completion of each user story during continuous integration.
Subjective or ambiguous statements make it difficult to test and verify a story. Collaborating on concrete, objective acceptance criteria is key to ensuring a shared understanding of what “done” means for each story.
Using INVEST Criteria for User Stories
Now that we’ve covered what each of the INVEST criteria represents, let’s look at how to actually apply them when writing Agile user stories.
Examples of Good and Bad INVEST User Stories
Viewing examples makes it easier to internalize what the INVEST standards look like in practice:
1. Independent User Story
Good Independent User Story: As a user, I want to update my profile picture so I can choose an image that represents me.
This story can be developed on its own without dependencies on other stories.
Bad Independent User Story: As a user, I want to update my profile so I can maintain accurate personal information.
This story is very broad and would likely require developing multiple dependent stories around profile sections.
2. Negotiable User Story
Good Negotiable User Story: As a user, I want to save products I’m interested in so I can review them later before purchasing.
This story suggests a user need without prescribing implementation details, leaving room for discussion.
Bad Negotiable User Story: As a user, I want the ability to add products to a persistent favorites wish list with a maximum of 20 items that are sorted alphabetically and displayed in the sidebar.
This story essentially dictates technical implementation details, leaving little room for collaboration.
3. Valuable User Story
Good Valuable User Story: As a user, I want to track my order status so I can see when my items have shipped.
The user value of being able to track shipment status is clear.
Bad Valuable User Story: As a developer, I want to implement an order-tracking feature.
This story is written from the developer’s perspective and does not indicate user value.
4. Estimable User Story
Good Estimable User Story: As a user, I want the ability to filter products by color so I can easily find items I want.
The story provides enough detail for developers to estimate the scope of work.
Bad Estimable User Story: As a user, I want to search products in various ways to help me find relevant items.
This story is vague and lacks the details needed to estimate development effort.
5. Small User Stroy
Good Small User Story: As a user, I want to see product images in search results so I can glance at items visually.
This story represents a thin vertical slice that can likely be completed in one Sprint.
Bad Small User Story: As a user, I want a comprehensive product search feature so I can always find items I’m looking for.
This story is an epic that is too large in scope to reasonably complete within a single Sprint.
6. Testable User Story
Good Testable User Story: As a user, I want to recover my password so that I can reset it by having a code emailed to me that is valid for 15 minutes.
The measurable outcomes make this story clearly testable.
Bad Testable User Story: As a user, I want to easily recover my password so I don’t get locked out of my account.
This story is vague and lacks objective criteria to test whether it was completed.
Using INVEST as Your Definition of Ready
The Definition of Ready (DoR) is a set of criteria each user story must satisfy before being accepted into a Sprint Backlog for development.
The INVEST principles provide an excellent foundation for a Definition of Ready. Some teams supplement INVEST with additional readiness criteria such as:
- Details necessary to implement the story are documented
- Relevant design sketches or UI mockups are included
- Story acceptance criteria defined
- Story dependencies identified
- Any non-functional requirements captured
- Performance criteria specified
- Security considerations noted
- Impact on other parts of the system checked
Customize your Definition of Ready based on your team’s needs. The goal is to ensure stories accepted into a Sprint are immediately actionable for developers and testers with all relevant details available. But take care not to make your Definition of Ready so stringent it becomes an obstacle to productivity.
Applying INVEST as part of your Definition of Ready helps instill a shared sense of quality and completeness for user stories before they are developed. This saves time, reduces confusion, and sets your Sprints up for success.
Conclusion
By consistently applying the INVEST criteria, teams can improve collaboration, transparency, alignment, and delivery when it comes to defining Agile user stories. The framework promotes the principles and values of Agile development.
While INVEST should be used thoughtfully, not dogmatically, it remains a simple yet powerful technique for creating excellent stories that enable the frequent delivery of valuable, working software. Teams that invest the small effort needed to master INVEST will unlock better performance, higher product quality, and greater customer satisfaction.
Remember, great Agile development starts with great user stories. Use INVEST as a tool to build shared understanding and deliver the maximum value.
