INVEST

How do we know if a Product Backlog Item (PBI) is of a good quality? We need to make sure it’s not too large to be implemented in a Sprint and that it can be tested in order to say that it’s “Done”.

To help us ensure a PBI is of good quality, we can use INVEST:

Independant – the PBI should be self-contained and not depend on other PBIs.

Negotiable – the PBI is not an explicit contract and should be open for discussion.

Valuable – it must deliver some form of value to the business

Estimable – the development team must be able to estimate how much effort it will take to implement the PBI.

Small – the PBI must fit within a Sprint.

Testable – we must be able to define tests/acceptance criteria for the PBI so that we know when it is Done.

Acceptance criteria

Acceptance criteria are used to define when a task is completed. They allow you to meet the Testable aspect of user stories when using INVEST.

They can cover both functional and non-functional criteria.

Example Acceptance Criteria

If we take the following as our user story:

“As a registered user, I want to book onto a training course of my choice.”

Some possible acceptance criteria could be:

• Send confirmation email to user when booking is saved
• Display correctly on PC, tablet and mobile phone.
• The form cannot be submitted without entering all required data.

Acceptance criteria are specific to a user story, while the Definition of Done covers all stories.

Duncan Halley is a certified Scrum Master (PSM I). You can read his blog here.

Follow him on Twitter: @duncanhalley