Boost Blog

Welcome back! So far in this mini-series I’ve covered the basics of user stories, and added some detail in the shape of acceptance criteria. Today’s post is about the INVEST model for writing user stories, but for that to make sense you need to know how an Agile project is run.

If you’re already familiar with Agile development, you might like to skip down the page to the section about the INVEST model. Otherwise, go make yourself a cup of tea and then settle in for a description of the Agile development process from the Product Owner’s point of view.

Agile / Scrum

Scrum is the form of Agile development that I’m most experienced with, and the one we follow here at Boost.

In Scrum, the development of your product (a website, a piece of software, an application) is split into a series of iterations, called sprints, each of which is usually between 2 and 4 weeks long. The number of sprints in your project might be determined by budget (how many staff, for how long, can we afford to put on this project?), time (how long until we need to have something live?) or experience (how long has this kind of project taken us in the past?).

At the centre of an Agile project is the team. As Mike Cohn writes:

Scrum relies on a self-organizing, cross-functional team. The scrum team is self-organizing in that there is no overall team leader who decides which person will do which task or how a problem will be solved. Those are issues that are decided by the team as a whole. The team is cross-functional so that everyone necessary to take a feature from idea to implementation is involved. These teams are supported by two specific individuals: a ScrumMasterand a product owner. The ScrumMaster can be thought of as a coach for the team, helping team members use the Scrum framework to perform at their highest level. The product owner represents the business, customers or users and guides the team toward building the right product.

Product Owners and Agile

I’ve been a Product Owner for a number of projects, and it’s a role I find immensely satisfying. You’re the voice of the customer on the project,  and it’s your job to make sure that the work the team is doing matches the business’s needs. As Product Owner you don’t necessarily need to be a technical expert, but you do need a deep understanding of your business and your customers, and the confidence to make fast  decisions.

The Product Owner manages the product backlog, the list of all the things the product needs to be and do. The product backlog is made up of user stories, and your first task in a new project is to sit down and write all the user stories you can think of right now (one of the beauties of Agile is that you can keep adding, removing and modifying user stories throughout the project) and then prioritise them.

Handing over the user stories: sprint planning

The sprint planning meeting is where you see the user stories being put into action. It’s attended by the Product Owner, the Scrum Master, and all the development team.

In the first part of the meeting the backlog will be put in front of the team (perhaps as a spreadsheet, or using a tool like Rally or Pivotal Tracker, or as a bunch of index cards). The team will then ask you questions about any of the user stories that aren’t immediately obvious, and you’ll talk about acceptance criteria. Through this conversation the team will decide which user stories will be tackled in the coming sprint, and what the sprint objective is. You might write this up as a sprint goal: “At the end of this sprint we’ll release the sign-up/log-in functionality to the live site”.

The user stories taken on for a sprint become the sprint backlog. This is all the team will focus on during the sprint – only the Product Owner will be looking at the rest of the product backlog.

The Product Owner isn’t usually present in the second part of the meeting, but I’ve sat in on these sessions (and kept my mouth shut – no doubt a surprise to anyone who knows me well). In this part of the meeting the team puts estimates on each of the user stories. Estimates can be expressed in different ways (story points, complexity points, team hours) but the general idea is that estimates show how much work a user story involves, and are used throughout the project to manage workloads, and predict and track how much work can be done in a given amount of time.

When the estimates are locked in, the team starts work.

User stories throughout a sprint

During a sprint each story will go through a number of stages:

• not started
• started
• in testing
• finished
• delivered
• accepted.

These stages are tracked through online tools like Rally or Pivotal Tracker or with a visible workspace.

Scrum Board by Drew Stephens on Flickr, released under a Creative Commons BY-SA license

During the sprint, the team will hold regular stand-up meetings (maybe every day, maybe on Mondays and Thursdays – whatever works for the pace of the project). As the name suggests, the meetings are held standing up – a physical signal to keep things snappy. At the stand-up the team members will update which stage each user story is at, and talk briefly on three points:

• What I did yesterday (or over the time since last stand-up)
• What I’m doing today
• What’s blocking me (anything that’s stopping them from progressing a user story – e.g. “I haven’t got the wireframes, so I’m blocked on starting the design”).

It’s good to have the Product Owner at the stand-ups, so they can answer any questions on the spot. You’re also likely to be called on throughout the sprint, to review wireframes, to give design briefs, to test out functionality, to answer questions about business needs. As work is completed, each user story will be assigned back to you to ‘accept’ or close: work on a story is complete when the user can achieve the stated goal, and all the acceptance criteria are met.

The aim is to get all the stories in the sprint backlog done before the sprint ends. Stories that run over several sprints are probably badly written (see the INVEST model at the end of this post).

At the sprint retrospective

At the end of the sprint, the team meets again to demonstrate the completed user stories to the Product Owner. Nothing should come as a surprise (you’ve been involved in the work throughout the sprint) but that doesn’t mean you won’t get a sense of delight at seeing finished functionality that’s ready to be released.

The Scrum Master will then lead the team (including the Product Owner) through a retrospective, an analysis of what went well in the sprint, what didn’t go well, what could be changed to make things go better, and any ideas that might improve performance or productivity.

Before the sprint retrospective you’ll have reviewed the product backlog (probably in a meeting with the Scrum Master) and done any rewriting or reprioritising of user stories. After the retrospective the sprint planning starts over again.

And at last, we come to INVEST

INVEST is a mnemonic that describes the qualities of a good user story:

Independent
Negotiable
Valuable to user or business
Estimable
Small
Testable

‘Good’ here means  ‘good for making this whole process work smoothly’, which is why we’ve walked through how a sprint plays out before coming to this definition.

Independent The story stands alone. Stories that are highly dependent on each other are hard to prioritise (“all the stories are equally important”) and hard to estimate (“I can’t put a time on that until we’ve finished that other story”). Problems with dependencies  can be solved by dividing stories differently, or combining several small stories into a single larger one.

Negotiable Remember card – conversation – confirmation? A story should be the starting point for a conversation and an opening for the team to suggest a solution, not a detailed description of how the Product Owner expects that feature or piece of functionality to be implemented.

Valuable It’s all about the end-user. If you can’t describe the value a customer is going to get out of your story, it’s not a good story.

Estimable No estimate, no entry into the sprint backlog. If there’s not enough information or definition to allow the team to put an estimate on a story, it doesn’t get started.

Small A story shouldn’t take longer than a sprint to finish. Any larger than this and it’s hard to estimate or plan for. It’s also likely to be hard to write acceptance criteria and to test.

Testable If you can’t test it, how do you know when a story’s done and working as it should?

Finis

I have one more post planned in this series (which, you’ll be glad to know, will be mercifully shorter than this one). It will look at how you can use user stories to involve people who aren’t working on a project but are interested in its progress and outcome (ie. stakeholders).

In the meantime, if you have any questions about working with Agile, just get in touch – we’re always happy to have a chat.