History:
In 1986, Hirotaka Takeuchi and Ikujiro Nonaka described a new holistic approach that would increase speed and flexibility in commercial new product development. They compared this new, holistic approach, in which the phases strongly overlap and the whole process is performed by one cross-functional team across the different phases, to rugby, where the whole team "tries to go the distance as a unit, passing the ball back and forth". The case studies came from the automotive, photo machine, computer, and printer industries.
Characteristics:
Scrum is a process skeleton that contains sets of practices and predefined roles. The main roles in Scrum are:
the “ScrumMaster”, who maintains the processes (typically in lieu of a project manager)
the “Product Owner”, who represents the stakeholders and the business
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. 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.
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.
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).
1. 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 the role not be combined with that of ScrumMaster.
2. 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.
3. 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 in hand. The role has also been referred to as servant-leader to reinforce these dual perspectives.
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.
1. 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.
2. Managers (including Project Managers)
People who will set up the environment for product development.
Meetings:
1. 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 only “pigs” may 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:
What have you done since yesterday?
What are you planning to do today?
Do you have any problems preventing you from accomplishing your goal? (It is the role of the ScrumMaster to facilitate resolution of these impediments. Typically this should occur outside the context of the Daily Scrum so that it may stay under 15 minutes.)
2. 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 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”
1. 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
2. Sprint Retrospective
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
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