Scrum (development)

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 It has been suggested that Sprint_(scrum) be merged into this article or section. (Discuss) Proposed since June 2011.

Scrum is an iterative, incremental framework for project management often seen in agile software development, a type of software engineering.

Although the Scrum approach was originally suggested for managing product development projects, its use has focused on the management of software development projects, and it can be used to run software maintenance teams or as a general project/program management approach.

Contents

[edit] History

In 1986, Hirotaka Takeuchi and Ikujiro Nonaka described a new approach to commercial product development that would increase speed and flexibility, based on case studies from manufacturing firms in the automotive, computer, photocopier, and printer industries.[1] They called this the holistic or rugby approach, as the whole process is performed by one cross-functional team across multiple overlapping phases, where the scrum (or whole team) "tries to go the distance as a unit, passing the ball back and forth".[1]

In 1991, DeGrace and Stahl first referred to this as the scrum approach.[2] In the early 1990s, Ken Schwaber used such an approach at his company, Advanced Development Methods, and Jeff Sutherland, with John Scumniotales and Jeff McKenna, developed a similar approach at Easel Corporation, and were the first to refer to it using the single word Scrum.[3]

In 1995, Sutherland and Schwaber jointly presented a paper describing the Scrum methodology at the Business Object Design and Implementation Workshop held as part of OOPSLA ’95 in Austin, Texas, its first public presentation.[4] Schwaber and Sutherland collaborated during the following years to merge the above writings, their experiences, and industry best practices into what is now known as Scrum.

In 2001, Schwaber teamed up with Mike Beedle to describe the method in the book Agile Software Development with Scrum.[5]

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.[6]

[edit] Characteristics

Scrum is a process skeleton that contains sets of practices and predefined roles. The main roles in Scrum are:

  1. the “ScrumMaster”, who maintains the processes (typically in lieu of a project manager)
  2. the “Product Owner”, who represents the stakeholders and the business
  3. the “Team”, a cross-functional group of about 7 people who do the actual analysis, design, implementation, testing, etc.

During each “sprint”, typically a two to four week period (with the length being decided by the team), the team creates a potentially shippable product increment (for example, working and tested software). The set of features that go into a sprint come from the product “backlog”, which is a prioritized set of high level requirements of work to be done. Which backlog items go into the sprint is determined during the sprint planning meeting. During this meeting, the Product Owner informs the team of the items in the product backlog that he or she wants completed. The team then determines how much of this they can commit to complete during the next sprint, and records this in the sprint backlog.[6] During a sprint, no one is allowed to change the sprint backlog, which means that the requirements are frozen for that sprint. Development 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. After a sprint is completed, the team demonstrates how to use the software.

Scrum enables the creation of self-organizing teams by encouraging co-location of all team members, and verbal communication between all team 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 team’s ability to deliver quickly and respond to emerging requirements.

Like other agile development methodologies, Scrum can be implemented through a wide range of tools. Many companies use universal software tools, such as spreadsheets to build and maintain artifacts such as the sprint backlog. There are also open-source and proprietary software packages dedicated to management of products under the Scrum process. Other organizations implement Scrum without the use of any software tools, and maintain their artifacts in hard-copy forms such as paper, whiteboards, and sticky notes.[7]

[edit] Roles

Scrum teams 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.

[edit] Core Scrum roles

The core roles in Scrum teams 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 Team 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 teams should have one Product Owner, and while they may also be a member of the Development Team, it is recommended that this role not be combined with that of ScrumMaster.[8]
Team
The Team is responsible for delivering the product. A Team is typically made up of 5–9 people with cross-functional skills who do the actual work (analyse, design, develop, test, technical communication, document, etc.). It is recommended that the Team be self-organizing and self-led, but often work with some form of project or team management.
ScrumMaster
Scrum is facilitated by a ScrumMaster, also written as Scrum Master, who is accountable for removing impediments to the ability of the team to deliver the sprint goal/deliverables. The ScrumMaster is not the team leader but acts as a buffer between the team and any distracting influences. The ScrumMaster ensures that the Scrum process is used as intended. The ScrumMaster is the enforcer of rules. A key part of the ScrumMaster’s role is to protect the team and keep them focused on the tasks at hand. The role has also been referred to as servant-leader to reinforce these dual perspectives.

[edit] Ancillary Scrum roles

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

Stakeholders (customers, vendors)
These are the people who enable the project and for whom the project will produce the agreed-upon benefit[s], which justify its production. They are only directly involved in the process during the sprint reviews.
Managers (including Project Managers)
People who will set up the environment for product development.

[edit] Agile Project Management with Scrum

Scrum has not only reinforced the interest in software project management, but also challenged the conventional ideas about such management. Scrum focuses on project management institutions where it is difficult to plan ahead with mechanisms for empirical process control, such as where feedback loops constitute the core element of product development compared to traditional command-and-control-oriented management. It represents a radically new approach for planning and managing software projects, bringing decision-making authority to the level of operation properties and certainties. Scrum reduces defects and makes the development process more efficient, as well as reducing long-term maintenance costs.[6]

[edit] 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 is timeboxed to 15 minutes
  • The meeting should happen at the same location and same time every day
During the meeting, each team member answers three questions:[9]
  • What have you done since yesterday?
  • What are you planning to do today?
  • Do you have any problems that would prevent you from accomplishing your goal? (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.)
Sprint Planning Meeting[10][11]
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 team
  • 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 + Team: dialog for prioritizing the Product Backlog
    • (2nd four hours) Team 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[12]
  • 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[13]
  • All team 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

[edit] Artifacts

[edit] Product backlog

The product backlog is a high-level list that is maintained throughout the entire project. It aggregates backlog items: broad descriptions of all potential features, prioritized as an absolute ordering by business value. It is therefore the “What” that will be built, sorted by importance. It is open and editable by anyone and contains rough estimates of both business value and development effort. Those estimates help the Product Owner to gauge the timeline and, to a limited extent prioritize. For example, if the “add spellcheck” and “add table support” features have the same business value, the one with the smallest development 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 property of the product owner. The associated development effort is however set by the Team.

[edit] Sprint backlog

The sprint backlog is the list of work the team must address during the next sprint. Features are broken down into tasks, which, as a best practice, should normally be between four and sixteen hours of work. With this level of detail the whole 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 team members as needed, according to the set priority and the team member skills. This promotes self-organization of the team, and developer buy-in.

The sprint backlog is the property of the team, and all included estimates are provided by the 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”.

[edit] Burn down

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,[14] 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.

[edit] Adaptive project management

The following are some general practices of Scrum:

[edit] Terminology

The following terminology is used in Scrum:[15]

[edit] Roles

Scrum Team
Product Owner, ScrumMaster and Team
Product Owner
The person responsible for maintaining the Product Backlog by representing the interests of the stakeholders.
ScrumMaster
The person responsible for the Scrum process, making sure it is used correctly and maximizing its benefits.
Team
A cross-functional group of people responsible for managing itself to develop the product.

[edit] 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.

[edit] Others

Impediment
Anything that prevents a team member from performing work as efficiently as possible.[16]
Sprint
A time period (typically 2–4 weeks) in which development occurs on a set of backlog items that the Team 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 Team to another, but must be consistent within one team.
Abnormal Termination
The Product Owner can cancel a Sprint if necessary.[17] The Product Owner may do so with input from the team, 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 team 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 team’s velocity.[18]
Point Scale
Relates to an abstract point system, used to discuss the difficulty of the task, without assigning actual hours. Common systems of scale are linear (1,2,3,4...), Fibonacci (1,2,3,5,8...), Powers-of-2 (1,2,4,8...), and Clothes size (XS, S, M, L, XL).[18]
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.

[edit] Scrum modifications

[edit] Scrum-ban

Scrum-ban is a software 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 team 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 team’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 team member is constantly employed.[19]

To illustrate each stage of work, teams working in the same space often use post-it notes or a large whiteboard.[20] In the case of decentralized teams, stage-illustration software, such as Assembla, ScrumWorks, or JIRA in combination with GreenHopper can be used to visualize each team’s user stories, defects and tasks divided into separate phases.

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

If desired, though, the teams 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.[21]

There are no set limiting values for unfinished work. Instead, each team 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.[22] A rule of thumb worth bearing in mind is that no team member should have more than two simultaneous selected tasks, and that on the other hand not all team members should have two tasks simultaneously.[21]

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 teams with multifaceted know-how, whereas Kanban makes specialized, functional teams possible.[23]

Since Scrum-ban is such a new development model, there is not much reference material. Kanban, on the other hand, has been applied in software development at least by Microsoft and Corbis.[24]

[edit] Product development

Scrum as applied to product development 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.

[edit] See also

Other Agile methods

[edit] References

  1. ^ a b Takeuchi, Hirotaka; Nonaka, Ikujiro (January–February 1986). "The New New Product Development Game" (PDF). Harvard Business Review. http://hbr.org/product/new-new-product-development-game/an/86116-PDF-ENG. Retrieved 2010-06-09. 
  2. ^ DeGrace, Peter; Stahl, Leslie Hulet (1990-10-01). Wicked problems, righteous solutions. Prentice Hall. ISBN 978-0-135-90126-7. 
  3. ^ Sutherland, Jeff (2004-10). "Agile Development: Lessons learned from the first Scrum" (PDF). http://www.scrumalliance.org/resources/35. Retrieved 2008-09-26. 
  4. ^ Sutherland, Jeffrey Victor; Schwaber, Ken (1995). Business object design and implementation: OOPSLA '95 workshop proceedings. The University of Michigan. p. 118. ISBN 3540760962. 
  5. ^ Schwaber, Ken; Beedle, Mike (2002). Agile software development with Scrum. Prentice Hall. ISBN 0130676349. 
  6. ^ a b c Schwaber, Ken (1 February 2004). Agile Project Management with SCRUM. Microsoft Press. ISBN 978-0-735-61993-7. 
  7. ^ Dubakov, Michael (2008). "Agile Tools. The Good, the Bad and the Ugly." (PDF). http://targetprocess.com/download/whitepaper/agiletools.pdf. Retrieved 2010-08-30. 
  8. ^ "Scrum, Scrum Developer Courses, Scrum Knowledge Assessment, Scrum Guide, Ken Schwaber - Scrum Guides". Scrum.org. 2009. http://www.scrum.org/scrumguides/. Retrieved 2010-04-03. 
  9. ^ Schwaber, p. 135
  10. ^ Schwaber, p. 133
  11. ^ Sprint, Planning (January–February 2009). Sprint Planning Rules. http://www.sprintplanning.com/SprintPlanningRules.aspx. Retrieved 2009-03-30. 
  12. ^ Schwaber, p. 137
  13. ^ Schwaber, p. 138
  14. ^ Invented by Mike Cohn, more info can be found here
  15. ^ Schwaber, pp. 141–143
  16. ^ Little, Joe (January 17, 2011), Impediment Management, Agile Consortium, http://agileconsortium.blogspot.com/2011/01/impediment-management.html 
  17. ^ "Scrum: Developed and Sustained". pp. 11. http://www.scrum.org/storage/scrumguides/Scrum%20Guide.pdf. 
  18. ^ a b "Scrum Effort Estimation and Story Points". http://scrummethodology.com/scrum-effort-estimation-and-story-points. 
  19. ^ p.5 Crisp.se
  20. ^ Leansoftwareengineering.com
  21. ^ a b Leansoftwareengineering.com
  22. ^ p.18 - 19 Crisp.se
  23. ^ p.22 - 23 Crisp.se
  24. ^ Infoq.com (The video and the summary)

[edit] Further reading

[edit] External links

Wikimedia Commons has media related to: Scrum

[edit] Videos

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