Scrum

Introduction

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.
There are several implementations of systems for managing the Scrum process, which range from yellow stickers and whiteboards, to software packages. One of Scrum’s biggest advantages is that it is very easy to learn and requires little effort to start using.

Sprint

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. The set of features that go into a sprint come from the product backlog.
During a sprint, no one is allowed to change the sprint backlog, which means that the requirements are frozen for that sprint. After a sprint is completed, the team demonstrates the use of the software.

Velocity:

  • How many story points the team can complete in one sprint.

Calculating Velocity

  • This sprint's estimated velocity = man-days available * last sprint's focus factor
  • Last sprint's focus factor = actual velocity / man-days available
  • Actual velocity = sum of the initial estimates of all stories that were completed last sprint (completed story points done last sprint)
  • 1 effective man-day ~= 6 effective man-hours
  • Default focus factor can be 70%
  • Lower focus factor in the next sprint is good when you have many defects in your plate

Team

  • Scrum enables the creation of self-organizing teams by encouraging co-location of all team members, and verbal communication across all team members and disciplines that are involved in the project.
  • Product owner and managers should not sit with the team
  • Scrum coach should talk to the scrum master not the whole team
  • Testers might not be part of the team
  • Fewer big independent teams is better than many small interfering teams.

Roles

Pig Roles

The Pigs are the ones committed to the project in the Scrum process—they are the ones with “their bacon on the line” and performing the actual work of the project.

  • ScrumMaster (or Facilitator): Scrum is facilitated by a ScrumMaster, whose primary job is to remove impediments to the ability of the team to deliver the sprint goal/deliverables. The ScrumMaster is not the leader of the team (as the team is self-organizing) 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.
  • Team: The team has the responsibility to deliver the product. A team is typically made up of 5–9 people with cross-functional skills who do the actual work (design, develop, test, technical communication, etc.).
  • Product Owner: The Product Owner represents the voice of the customer. He/she ensures that the Scrum Team works with the “right things” from a business perspective. The Product Owner writes customer-centric items (typically user stories), prioritizes them and then places them in the product backlog. A Product Owner can be a member of the Scrum Team but cannot be a ScrumMaster.

Chicken roles

Chicken roles are not part of the actual Scrum process, but must be taken into account. They are people for whom the software is being built.

  • Stakeholders (customers, vendors)
  • Managers

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 only “pigs” may speak
  • The meeting is timeboxed to 15-30 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 a stand up meeting
  • When the agile team is not co-located the standups tend to become longer because the technical discussions will happen there.

Scrum of scrums

  • Held each day, normally after the daily scrum.
  • These meetings allow clusters of teams to discuss their work, focusing especially on areas of overlap and integration.
  • A designated person from each team attends.

Sprint Planning

  • At the beginning of the sprint cycle (every 7–30 days), a “Sprint Planning Meeting” is held.
  • The *output* of this meeting is to:
    • select stories to include in the sprint (and estimating stories-planning poker)
    • decide on sprint goal
    • list team members
    • create sprint backlog
    • break sprint stories into tasks
    • decide on a demo date
    • decide on time and date of daily scums
  • 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 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
  • Product backlog should be ready before sprint planning meeting

Tech Stories

Tech stories or non-functional stories are better to be avoided. They can be transformed into business stories or included into one. If this can not be done they should become separate stories.

Sprint Review

  • At the end of a sprint cycle
  • 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

  • At the end of a sprint cycle
  • All team members, product owner and coaches 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 a high-level document for the entire project.
  • It contains backlog items (stories): broad descriptions of all required features, wish-list items, etc. prioritized by business value.
  • It is the “What” that will be built in business terms/level. It is open and editable by anyone and contains rough estimates of both business value and development effort.
  • The product backlog is the property of the *Product Owner*. Business value is set by the Product Owner. Development effort is set by the Team.
  • fields in the product backlog table/document:
id name importance estimate how to demo (acceptance criteria) notes

Sprint backlog

  • The sprint backlog is a document containing information about how the team is going to implement the features for the upcoming sprint.
  • Features are broken down into tasks; as a best practice, tasks are normally estimated between four and sixteen hours of work.
  • 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.
  • The sprint backlog is the property of the Team and editable by them. Estimations are set 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”.
  • Sprint backlog items comes from product backlog.

Burn down

  • 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.
  • The chart has date on x-axis and estimated work remaining (story points) on y-axis. Ideally it should be a downward chart.

Reference

page revision: 29, last edited: 05 Aug 2011 01:15
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