User story

History

With Extreme Programming (XP)., user stories were a part of the planning game.

In 2001, Ron Jeffries proposed a "Three Cs" formula for user story creation:

A Card (or often a post-it note) is a tangible durable physical token to hold the concepts;

A Conversation between the stakeholders (customers, users, developers, testers, etc.). It is verbal and often supplemented by documentation;

The Confirmation ensures that the objectives of the conversation have been reached.

Creating user stories

User stories are written by or for users or customers to influence the functionality of the system being developed. In some teams, the product manager (or product owner in Scrum), is primarily responsible for formulating user stories and organizing them into a product backlog. In other teams, anyone can write a user story. User stories can be developed through discussion with stakeholders, based on personas or simply made up.

Format

User stories may follow one of several templates. A team at Connextra developed the a popular user-story template in 2001:

"As a <role>, I want <goal/desire> so that <benefit>"

Mike Cohn, a well-known author on user stories, regards the "so that" clause as optional:

"As a <role>, I want <goal/desire>"

Chris Matts suggested that "hunting the value" was the first step in successfully delivering software, and proposed this alternative as part of Feature Injection:

"In order to <receive benefit> as a <role>, I want <goal/desire>"

Another template based on the Five Ws specifies:

"As <who> <when> <where>, I <what> because <why>."

A template developed at Capital One in 2004 during their initial adoption of Agile methods focuses on the functionality and specifies:

"As a <role>, I can <action with system> so that <external benefit>"

Another template based on Rachel Davies' popular template:

"As <persona> ,I want <what?> so that <why?>"

where a persona is a fictional stakeholder (e.g. user). A persona may include a name, picture; characteristics, behaviours, attitudes, and a goal which the product should help them achieve.

Examples

Screening Quiz (Epic Story)

As the HR manager, I want to create a screening quiz so that I can understand whether I want to send possible recruits to the functional manager.

Quiz Recall

As a manager, I want to browse my existing quizzes so I can recall what I have in place and figure out if I can just reuse or update an existing quiz for the position I need now.

Limited Backup

As a user, I can indicate folders not to backup so that my backup drive isn't filled up with things I don't need saved.

Usage

As a central part of many agile development methodologies, such as in XP's planning game, user stories define what has to be built in the software project. User stories are prioritized by the customer (or the product owner in Scrum) to indicate which are most important for the system and will be broken down into tasks and estimated by the developers. One way of estimating is via a Fibonacci scale.

When user stories are about to be implemented, the developers should have the possibility to talk to the customer about it. The short stories may be difficult to interpret, may require some background knowledge or the requirements may have changed since the story was written.

Every user story must at some point have one or more acceptance tests attached, allowing the developer to test when the user story is done and also allowing the customer to validate it. Without a precise formulation of the requirements, prolonged nonconstructive arguments may arise when the product is to be delivered.

Benefits

There is no good evidence that using user stories increases software success or developer productivity. However, user stories facilitate sensemaking without undue problem structuring, which is linked to success.

Limitations

Limitations of user stories include:

Scale-up problem

User stories written on small physical cards are hard to maintain, difficult to scale to large projects and troublesome for geographically distributed teams.

Vague, informal and incomplete

User story cards are regarded as conversation starters. Being informal, they are open to many interpretations. Being brief, they do not state all of the details necessary to implement a feature. Stories are therefore inappropriate for reaching formal agreements or writing legal contracts.

Lack of non-functional requirements

User stories rarely include performance or non-functional requirement details, so non-functional tests (e.g. response time) may be overlooked.

Story map

A story map is a graphical, two-dimensional visualization of the product backlog. At the top of the map are the headings under which stories are grouped, usually referred to as 'epics' (big coarse-grained user stories), 'themes' (collections of related user stories) or 'activities'. These are identified by orienting at the user’s workflow or "the order you'd explain the behavior of the system". Vertically, below the epics, the actual story cards are allocated and ordered by priority. The first horizontal row is a "walking skeleton" and below that represents increasing sophistication.

In this way it becomes possible to describe even big systems without losing the big picture.

Comparing with use cases

A use case has been described as "a generalized description of a set of interactions between the system and one or more actors, where an actor is either a user or another system." While user stories and use cases have some similarities, there are several differences between them.

Kent Beck, Alistair Cockburn, Martin Fowler and others discussed this topic further on the c2.com wiki (the home of extreme programming).