In Agile development, a spike is a type of user story specifically designed for investigation or research. Its primary purpose is to gather more information about a technical problem, a proposed solution, or a user requirement before the team can accurately estimate the effort required to implement it.
Understanding the Purpose of Spikes
As stated in the reference, "A spike story in Agile is a user story that needs more information so the team can estimate how long the story will take to complete." This highlights the core reason for using spikes: reducing uncertainty. When a complex or unfamiliar task arises, a team might not have enough clarity to provide a reliable estimate. A spike allows them to dedicate time to explore the unknowns.
Key reasons for using spikes include:
- Reducing Risk: Investigating technical feasibility or identifying potential challenges early.
- Improving Estimates: Gaining the necessary knowledge to provide a more accurate estimate for the related user story or feature.
- Exploring Solutions: Researching different approaches or technologies to find the most suitable one.
- Gathering Information: Understanding complex requirements or dependencies.
Spikes are Timeboxed
The reference also notes, "Agile teams typically have a set amount of time outlined for spikes, which is why spike stories are often referred to as timeboxed investigations." This is a crucial characteristic. Spikes are not open-ended research projects. They are assigned a specific timebox (e.g., a few hours, one or two days) within a sprint.
The outcome of a spike is not typically working software, but rather:
- Knowledge gained
- Answers to specific questions
- Reduced uncertainty
- Information necessary to estimate the original story
- Perhaps a small proof-of-concept or diagram
If the allocated time runs out and the required information isn't fully gathered, the team can choose to schedule another spike or make a decision based on the information they did find.
Technical vs. Functional Spikes
Spikes can broadly be categorized into two types:
- Technical Spikes: These focus on understanding technical challenges, exploring new technologies, evaluating integration points, or prototyping potential solutions.
- Example: Investigating how to integrate with a new third-party API.
- Functional/Business Spikes: These focus on gathering more information about user requirements, workflow details, or clarifying business rules.
- Example: Researching different user scenarios to understand the acceptance criteria for a complex feature.
Spikes in Practice
- Spikes are often added to the sprint backlog like regular stories, but their acceptance criteria might focus on the information gained rather than working code.
- The output of a spike typically informs subsequent user stories, allowing the team to break down large or complex tasks and estimate them more accurately.
- They help prevent teams from committing to work they don't fully understand, reducing the likelihood of missed deadlines or unexpected blockers.
Using spikes effectively helps Agile teams navigate uncertainty, improve planning, and ultimately deliver value more predictably.
