Scrum (development)

The Scrum process.

Scrum is an iterative and incremental methodology for software projects and product- or application-development. It is an agile software development methodology.

History

In 1986, Hirotaka Takeuchi and Ikujiro Nonaka described a new tactic that would increase speed and flexibility at the cost of design and quality, based on case studies from manufacturing firms in the automotive, photocopier, restaurants food and printer manufacturers. They called this the holistic or rugby approach, as the whole process is performed by one cross-functional group across multiple overlapping phases, where the group "tries to go the distance as a unit, passing the ball back and forth".

In 1991, DeGrace and Stahl first referred to this as the scrum. In rugby, a scrum refers to the manner of restarting the game after a minor infraction. In the early 1990s, Ken Schwaber used what would become Scrum at his company, Advanced Development Methods, and Jeff Sutherland, with John Scumniotales and Jeff McKenna, came up with a similar approach at Easel Corporation, and were the first to refer to it using the single word Scrum.

In 1995, Sutherland and Schwaber jointly presented a paper describing the Scrum method at the Business Object Design and Implementation Workshop held as part of OOPSLA ’95 in Austin, Texas, its first public presentation. Schwaber and Sutherland worked together to merge the above writings into what is now known as Scrum.

In 2001, Schwaber worked with Mike Beedle to describe the method in the book Agile with Scrum.

Although the word is not an acronym, some companies implementing the process have been known to spell it with capital letters as SCRUM. This may be due to one of Ken Schwaber’s early papers, which capitalized SCRUM in the title.

Characteristics

Scrum contains sets of methods and predefined roles. The main roles in Scrum are:

1. the "ScrumMaster", who ensures the process is followed and removes impediments
2. the "Product Owner", who represents the stakeholders and the business
3. the "Development Team", a group who does the coding, implementation, testing, etc.

Sprint

A sprint is the basic unit in Scrum. Sprints last between one week and one month, and are a "timeboxed" (i.e. restricted to a specific duration) effort of a constant length.

Each sprint is preceded by a meeting, where the tasks for the sprint are initiated for the sprint goal, and followed by a retrospective meeting, where the progress is reviewed and lessons for the next sprint are identified.

During each sprint, the group creates finished portions of a product. The work items that go into a sprint come from the product backlog, which is a prioritized list of requirements. Which backlog items go into the sprint is determined during the sprint planning meeting. During this meeting, the Product Owner informs the group of the items in the product backlog that he or she wants completed (the ones with the highest priority). The group then determines how much of this they can commit to complete during the next sprint, and records this in the sprint backlog. During a sprint, no one is allowed to change the sprint backlog, which means that the requirements are frozen for that sprint. Management is timeboxed such that the sprint must end on time; if requirements are not completed for any reason they are left out and returned to the product backlog.

Scrum enables the creation of self-organizing groups by encouraging co-location of all group members, and verbal communication between all group members and disciplines in the project.

A key principle of Scrum is its recognition that during a project the customers can change their minds about what they want and need (often called requirements churn), and that unpredicted challenges cannot be easily addressed in a traditional predictive or planned manner. As such, Scrum adopts an empirical approach—accepting that the problem cannot be fully understood or defined, focusing instead on maximizing the group’s ability to deliver quickly and respond to emerging requirements.

Like other agile methods, Scrum can be implemented through a wide range of tools. Many companies use universal tools, such as spreadsheets to build and maintain artifacts such as the sprint backlog. There are also open-source and proprietary packages dedicated to management of products under the Scrum process. Other organizations implement Scrum without the use of any tools, and maintain their artifacts in hard-copy forms such as paper, whiteboards, and sticky notes.

Roles

Scrum groups consist of three core roles and a range of ancillary roles—core roles are often referred to as pigs and ancillary roles as chickens (after the story The Chicken and the Pig).

Core roles

The core roles in Scrum groups are those committed to the project in the Scrum process—they are the ones producing the product (objective of the project).

Product Owner

The Product Owner represents the voice of the customer and is accountable for ensuring that the Group delivers value to the business. The Product Owner writes customer-centric items (typically user stories), prioritizes them, and adds them to the product backlog. Scrum groups should have one Product Owner, and while they may also be a member of the Management Group, it is recommended that this role not be combined with that of ScrumMaster.

Development Team

The Development Team is responsible for delivering potentially shippable product increments at the end of each Sprint. A Development Team is made up of 3–9 people with cross-functional skills who do the actual work (analyse, design, develop, test, technical communication, document, etc.). The Development Team in Scrum is self-organizing, even though they may interface with project management organizations (PMOs).

Scrum Master

Scrum is facilitated by a Scrum Master, sometimes written as ScrumMaster, who is accountable for removing impediments to the ability of the group to deliver the sprint goal/deliverables. The Scrum Master is not the group leader but acts as a buffer between the group and any distracting influences. The Scrum Master ensures that the Scrum process is used as intended. The Scrum Master is the enforcer of rules. A key part of the Scrum Master’s role is to protect the Development Team and keep it focused on the tasks at hand. The role has also been referred to as a servant-leader to reinforce these dual perspectives.

Ancillary roles

The ancillary roles in Scrum groups are those with no formal role and infrequent involvement in the Scrum process—but nonetheless, must be taken into account.

Stakeholders (customers, vendors)

These are the people who enable the project and for whom the project produces the agreed-upon benefit[s] that justify its production. They are only directly involved in the process during the sprint reviews.

Managers

People who control the environment.

Agile project management with scrum

Scrum has not only reinforced the interest in project management, but also challenged the conventional ideas about such management. Scrum focuses on inexperienced project management institutions where it is difficult to plan ahead with mechanisms for process control, where feedback loops constitute the core element of traditional command-and-control oriented management.^{[citation needed]} It represents a radically new approach for planning and managing projects, bringing decision-making authority to the level of operation properties and certainties.

Meetings

Daily Scrum

Each day during the sprint, a project status meeting occurs. This is called a daily scrum, or the daily standup. This meeting has specific guidelines:

• The meeting starts precisely on time.
• All are welcome, but normally only the core roles speak
• The meeting length is set (timeboxed) to 15 minutes
• The meeting should happen at the same location and same time every day

During the meeting, each group member answers three questions:

• What have you done since yesterday?
• What are you planning to do today?
• Any impediments/stumbling blocks?

It is the role of the ScrumMaster to facilitate resolution of these impediments, although the resolution should occur outside the Daily Scrum itself to keep it under 15 minutes.

Backlog grooming: storytime

The group should spend time during a sprint doing backlog grooming. This is the process of: estimating the existing backlog using effort/points, refining the acceptance criteria for individual stories, and breaking larger stories into smaller stories.

• Meetings should not be longer than an hour
• Meeting does not include breaking stories into tasks
• Group can decide how many meetings are needed per week.

Scrum of Scrums

Each day normally after the Daily Scrum.

• These meetings allow clusters of groups to discuss their work, focusing especially on areas of overlap and integration.
• A designated person from each group attends.

The agenda will be the same as the Daily Scrum, plus the following four questions:

• What has your group done since we last met?
• What will your group do before we meet again?
• Is anything slowing your group down or getting in their way?
• Are you about to put something in another group’s way?

Sprint planning meeting

At the beginning of the sprint cycle (every 7–30 days), a “Sprint planning meeting” is held.

• Select what work is to be done
• Prepare the Sprint Backlog that details the time it will take to do that work, with the entire group
• Identify and communicate how much of the work is likely to be done during the current sprint
• Eight hour time limit
  • (1st four hours) Product Owner + Group: dialog for prioritizing the Product Backlog
  • (2nd four hours) Group only: hashing out a plan for the Sprint, resulting in the Sprint Backlog

At the end of a sprint cycle, two meetings are held: the “Sprint Review Meeting” and the “Sprint Retrospective”

Sprint review meeting

• Review the work that was completed and not completed
• Present the completed work to the stakeholders (a.k.a. “the demo”)
• Incomplete work cannot be demonstrated
• Four hour time limit

Sprint retrospective

• All group members reflect on the past sprint
• Make continuous process improvements
• Two main questions are asked in the sprint retrospective: What went well during the sprint? What could be improved in the next sprint?
• Three hour time limit

Artifacts

Product Backlog

The product backlog is an ordered list of "requirements" that is maintained for a product. It contains Product Backlog Items that are ordered by the Product Owner based on considerations like risk, business value, dependencies, date needed, etc. The features added to the backlog are commonly written in story format (See terminology below). The product backlog is the “What” that will be built, sorted in the relative order it should be built in. It is open and editable by anyone, but the Product Owner is ultimately responsible for ordering the stories on the backlog for the Development Team. The product backlog contains rough estimates of both business value and management effort, these values are often stated in story points using a rounded Fibonacci sequence. Those estimates help the Product Owner to gauge the timeline and may influence ordering of backlog items. For example, if the “add spellcheck” and “add table support” features have the same business value, the one with the smallest management effort will probably have higher priority, because the ROI (Return on Investment) is higher.

The Product Backlog, and business value of each listed item is the responsibility of the Product Owner. The estimated effort to complete each backlog item is, however, determined by the Development Team.

Sprint backlog

The sprint backlog is the list of work the Development Team must address during the next sprint. The list is derived by selecting stories/features from the top of the product backlog until the Development Team feels it has enough work to fill the sprint. This is done by the Development Team asking "Can we also do this?" and adding stories/features to the sprint backlog. The Development Team should keep in mind the velocity of its previous Sprints (total story points completed from each of the last sprints stories) when selecting stories/features for the new sprint, and use this number as a guide line of how much "effort" they can complete.

The stories/features are broken down into tasks by the Development Team, which, as a best practice, should normally be between four and sixteen hours of work. With this level of detail the Development Team understands exactly what to do, and potentially, anyone can pick a task from the list. Tasks on the sprint backlog are never assigned; rather, tasks are signed up for by the group members as needed during the daily scrum, according to the set priority and the Development Team member skills. This promotes self-organization of the Development Team, and developer buy-in.

The sprint backlog is the property of the Development Team, and all included estimates are provided by the Development Team. Often an accompanying task board is used to see and change the state of the tasks of the current sprint, like “to do”, “in progress” and “done”.

Burn down

A sample burn down chart for a completed iteration, showing remaining effort and tasks for each of the 21 work days of the 1-month iteration.

Main article: burn down chart

The sprint burn down chart is a publicly displayed chart showing remaining work in the sprint backlog. Updated every day, it gives a simple view of the sprint progress. It also provides quick visualizations for reference. There are also other types of burndown, for example the release burndown chart that shows the amount of work left to complete the target commitment for a Product Release (normally spanning through multiple iterations) and the alternative release burndown chart, which basically does the same, but clearly shows scope changes to Release Content, by resetting the baseline.

It should not be confused with an earned value chart.

Terminology

The following terminology is used in Scrum:

Roles

Scrum Team

Product Owner, ScrumMaster and Group

Product Owner

The person responsible for maintaining the Product Backlog by representing the interests of the stakeholders, and ensuring the value of the work the Development Team does.

Scrum Master

The person responsible for the Scrum process, making sure it is used correctly and maximizing its benefits.

Development Team

A cross-functional group of people responsible for delivering potentially shippable increments of Product at the end of every Sprint.

Artifacts

Sprint burn down chart

Daily progress for a Sprint over the sprint’s length.

Product backlog

A prioritized list of high level requirements.

Sprint backlog

A prioritized list of tasks to be completed during the sprint.

Others

Story

A feature that is added to the backlog is commonly referred to as a story and has a specific suggested structure. The structure of a story is: "As a <user type> I want to <do some action> so that <desired result>" This is done so that the management group can identify the user, action and required result in a request and is a simple way of writing requests that anyone can understand. Example: As a wiki user I want a tools menu on the edit screen so that I can easily apply font formatting.

Impediment

Anything that prevents a group member from performing work as efficiently as possible.

Sprint

A time period (typically 1–4 weeks) in which product management occurs on a set of backlog items that the Group has committed to. Also commonly referred to as a Time-box.

Sashimi

A report that something is "done". The definition of "done" may vary from one Scrum Group to another, but must be consistent within one group.

Abnormal Termination

The Product Owner can cancel a Sprint if necessary. The Product Owner may do so with input from the group, scrum master or management. For instance, management may wish to cancel a sprint if external circumstances negate the value of the sprint goal. If a sprint is abnormally terminated, the next step is to conduct a new Sprint planning meeting, where the reason for the termination is reviewed.

Planning Poker

In the Sprint Planning Meeting, the group sits down to estimate its effort for the stories in the backlog. The Product Owner needs these estimates, so that he or she is empowered to effectively prioritize items in the backlog and, as a result, forecast releases based on the group’s velocity.

Point Scale/Effort/Story points

Relates to an abstract point system, used to discuss the difficulty of the story, without assigning actual hours. The most common scale used is a rounded Fibonacci sequence (1,2,3,5,8,13,20,40,100), although some groups use linear scale (1,2,3,4...), Powers-of-2 (1,2,4,8...), and Clothes size (XS, S, M, L, XL).

Tasks

Added to the story at the beginning of a sprint and broken down into hours. Each task should not exceed 12 hours but it's common for groups to insist that a task take no more than a day to finish.

Definition of Done (DoD)

The exit-criteria to determine whether a product backlog item is complete. In many cases the DoD requires that all regression tests should be successful.

Velocity

The total effort a group is capable of in a sprint. The number is derived by adding all the story points from the last sprints stories/features. This is a guideline for the group and assists them in understanding how many stories they can do in a sprint.

Scrum modifications

Scrum-ban

Scrum-ban is a production model based on Scrum and Kanban. Scrum-ban is especially suited for maintenance projects or (system) projects with frequent and unexpected user stories or programming errors. In such cases the time-limited sprints of the Scrum model are of no appreciable use, but Scrum’s daily meetings and other practices can be applied, depending on the group and the situation at hand. Visualization of the work stages and limitations for simultaneous unfinished user stories and defects are familiar from the Kanban model. Using these methods, the group’s workflow is directed in a way that allows for minimum completion time for each user story or programming error, and on the other hand ensures each group member is constantly employed.

To illustrate each stage of work, groups working in the same space often use post-it notes or a large whiteboard. In the case of decentralized groups, stage-illustration such as Assembla, ScrumWorks, Rational Group Concert or JIRA in combination with GreenHopper can be used to visualize each group’s user stories, defects and tasks divided into separate phases.

In their simplest, the tasks or usage stories are categorized into the work stages

• Unstarted
• Ongoing
• Completed

If desired, though, the groups can add more stages of work (such as “defined”, “designed”, “tested” or “delivered”). These additional phases can be of assistance if a certain part of the work becomes a bottleneck and the limiting values of the unfinished work cannot be raised. A more specific task division also makes it possible for employees to specialize in a certain phase of work.

There are no set limiting values for unfinished work. Instead, each group has to define them individually by trial and error; a value too small results in workers standing idle for lack of work, whereas values too high tend to accumulate large amounts of unfinished work, which in turn hinders completion times. A rule of thumb worth bearing in mind is that no group member should have more than two simultaneous selected tasks, and that on the other hand not all group members should have two tasks simultaneously.

The major differences between Scrum and Kanban are derived from the fact that, in Scrum, work is divided into sprints that last a certain amount of time, whereas in Kanban the workflow is continuous. This is visible in work stage tables, which in Scrum are emptied after each sprint. In Kanban all tasks are marked on the same table. Scrum focuses on groups with multifaceted know-how, whereas Kanban makes specialized, functional groups possible.

Since Scrum-ban is such a new management model, there is not much reference material. Kanban, on the other hand, has been applied by Microsoft and Corbis.

Product management

Scrum as applied to product management was first referred to in "New New Product Development Game" (Harvard Business Review 86116:137–146, 1986) and later elaborated in "The Knowledge Creating Company" both by Ikujiro Nonaka and Hirotaka Takeuchi (Oxford University Press, 1995). Today there are records of Scrum used to produce financial products, Internet products, and medical products by ADM.

Project management tools that support scrum

• Banana Scrum
• CollabNet ScrumWorks Pro
• Hansoft
• IBM Rational Team Concert
• Ice Scrum
• JIRA using Green Hopper plugin
• Microsoft Team Foundation Server
• OneDesk
• PangoScrum
• Pivotal Tracker
• Rally
• ScrumDo
• Scrumy
• Sprintometer
• Tinypm
• Version 1
• Visual Studio 2010

See also

• Kaizen
• Code monkey
• Extreme programming (XP)
• TDD
• FDD
• Lean
• DSDM

Further reading

• "The Scrum Guide". 2011. http://www.scrum.org/storage/scrumguides/Scrum_Guide.pdf. Retrieved 2011-12-3. 
• "The Scrum Agile Process for Small Groups". 2000. http://members.cox.net/risingl1/Articles/IEEEScrum.pdf. Retrieved 2007-03-15. 
• Deemer, Pete; Benefield, Gabrielle; Larman, Craig; Vodde, Bas (2009). "The Scrum Primer". http://scrumtraininginstitute.com/home/stream_download/scrumprimer. Retrieved 2009-06-01. 
• Kniberg, Henrik. "Scrum and XP from the Trenches". http://www.infoq.com/minibooks/scrum-xp-from-the-trenches. Retrieved 2010-08-09. 

External links

• Scrum.org
• Scrum Alliance, non-profit
• Agile Alliance’s Scrum library
• A Scrum Process Description by the Eclipse Process Framework (EPF) Project
• BPMN process diagram of Scrum
• A six-page illustrated Scrum reference
• Burn Down Chart Tutorial: Simple Agile Project Tracking (Scrum)

Videos and slides

• Jeff Sutherland in Scrum Tuning: Lessons learned from Scrum implementation at Google Retrieved 2007-12-15
• Ken Schwaber in Scrum et al. Retrieved 2008-01-19
• Jeff Sutherland in Hyperproductive Distributed Scrum Groups
• Jeff Sutherland in Self-Organization: The Secret Sauce for Improving your Scrum group
• Bruno Sbille and his group in Scrum applied on a real-world project (HD) Retrieved 2009-05-19
• Scrum at Large: Managing 100 People and More
• Andrea Tomasini's keynote about Agile in an Enterprise