化緊急為有序：Sprint緩衝區設計完整指南（二）
中英對照翻譯
💡來源出處：Scrum Pattern — Illegitimus Non Interruptus
設定三項簡單規則，使組織能自我調整，避免打斷生產。
Set up three simple rules that will cause the organization to self-organize to avoid disrupting production.
這項策略將幫助團隊在 Sprint 期間重新規劃，提高交付完整產品增量的可能性。
This strategy will help the team replan during the Sprint to raise the chances of delivering the complete Product Increment.
1. 團隊根據歷史數據，為突發工作項目建立一個緩衝區。比如，如果團隊的平均工作量中有三分之一是來自 Sprint 期間意外發生的非計劃的工作，而團隊的平均速度為 60 點，則團隊為突發緩衝區保留 20 點。
1. The team creates a buffer for unexpected items based on historical data. For example, let’s say that a third of the team’s work on average comes from unplanned work coming into the Sprint unexpectedly. If the team velocity averages 60 points, the team reserves 20 points for the interrupt buffer.
2. 所有棘手的請求，必須經由產品負責人進行分類。（比如，網頁拼錯字或編譯錯誤，是明顯的錯誤，這些的解決方案顯而易見，所以不需要額外的商業洞察力。開發人員可以在 time-boxed 內解決這些問題，而把更大的問題提交給產品負責人。）產品負責人會給予某些工作項目低的優先順序，因為它們對商業計劃無關緊要。產品負責人會將其他許多工作項目，推遲到後續的 Sprint，即使它們具有立即價值。少數工作項目是關鍵項目，團隊必須在當前的 Sprint 完成，因此產品負責人會將它們放入突發緩衝區（interrupt buffer）。
2. All non-trivial requests must go through the Product Owner for triage. (Web page spelling errors and compilation errors are examples of trivial errors where the fix is so obvious that there is no benefit from additional business insight. Developers may spend some small, time-boxed amount of time addressing even non-trivial defects before escalating to the Product Owner.) The Product Owner will give some items low priority if there is no perceived value relative to the business plan. The Product Owner will push many other items to subsequent Sprints even if they have immediate value. A few items are critical and the team must complete them in the current Sprint, so the Product Owner puts them into the interrupt buffer.
3. 如果緩衝區（buffer）內的工作，開始滿出來，也就是說產品負責人將超過 20 點的工作加入 Sprint，Scrum Team 必須自動中止 Sprint，重新規劃，並通知管理層日期將推遲。
3. If the buffer starts to overflow, that is, the Product Owner puts one point more than 20 points into the Sprint, the Scrum Team must automatically abort, the Sprint must be replanned, and the Product Owner notifies management that dates will slip.
管理層必須同意上述這些規則，並嚴格執行。對於團隊和其他利害關係人，產品負責人必須始終有空（能被找到）。在產品負責人缺席時，Scrum Team 應指定一名成員臨時擔任此角色。
It is essential to get management agreement on these rules and to enforce them. The Product Owner must always be available to the team and other stakeholders. In the Product Owner’s absence, the Scrum Team should designate one of its own to temporarily fill that role.
產品負責人調整緩衝區大小（buffer size），以平衡短期的顧客滿意度和未來收益產生之間的關係。通常，產品負責人可以根據第三方的顧客滿意度指標，來調整緩衝區大小。
The Product Owner balances the buffer size to balance short-term customer satisfaction with future revenue generation. Often, a Product Owner has third-party metrics on customer satisfaction that he or she can adjust up or down with buffer size.
這項策略跟解決 Sprint 中來自待辦工作項目的缺陷（請參考 Good Housekeeping）無關，也和產品負責人在 Sprint Planning 中，分配給 Sprint 用來減少技術負債的 PBI 無關。有低的缺陷容忍度，通常會增加速度，但當臨時安插進來要做的事超出緩衝區時，通常會導致速度至少減少 50%。產品負責人必須用常識去平衡這些因素（參閱 Whack the Mole）。
This strategy is independent of the focus on fixing all defects that arise in the Sprint from backlog items worked on during the Sprint (see Good Housekeeping). It is also independent of PBIs assigned to a Sprint by the Product Owner as part of Sprint Planning to reduce technical debt. Low defect tolerance increases velocity in general, but exceeding the buffer typically generates at least a 50 percent reduction in velocity. The Product Owner must use common sense to balance these forces. See Whack the Mole.
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這些規則無法避免地會導致個體的自我調整，自我調整的原因是為了避免 Sprint 的崩潰，因為沒有人希望被視為導致 Sprint 失敗的直接原因。
These rules will invariably cause individuals to self-organize to avoid blowing up a Sprint, as no individual wants to be seen as the direct cause of Sprint failure.
更好的事情是，緩衝區通常不會被完全佔滿，這使團隊得以提前完成，從待辦工作清單中拉取工作項目或處理障礙物。這個動作相當重要，因為提前完成的團隊會加速更快（請參閱 Teams That Finish Early Accelerate Faster）。此外，如果團隊使用昨天的天氣（Yesterday’s Weather） 來安排緩衝區，那麼緩衝區會幾乎從不被填滿，並且緩衝區大小將持續縮小，最終使突發問題消失。
Even better, the buffer will tend to never be full, allowing the team to finish early and pull forward from the backlog and/or work on removing impediments. This is important because Teams That Finish Early Accelerate Faster. Furthermore, if the team uses Yesterday’s Weather to size the buffer and the buffer almost never fills up, the buffer size continuously gets smaller, making the interrupt problem go away.
與預期相反的是，這並不會導致關鍵問題被隱藏或未解決。產品負責人會將任何關鍵工作項目，放入產品待辦工作清單中。這有助於團隊提高速度，增加未來 Sprint 的產出。這一般能空出足夠的時間，以便處理關鍵工作項目，甚至能經常保有多餘的應變能力。
Counterintuitively, this does not cause critical problems to be hidden or unresolved. The Product Owner will put any critical items on the Product Backlog. This helps the team increase its velocity and increase the output of future Sprints. This typically allows more than enough time to address critical items and often with spare capacity.
團隊會展現對產品的高度自豪感，願意暫停自己的工作，以維護產品的品質和名聲。其他相關的 Scrum Pattern 包含：Product Owner、Product Backlog、Teams That Finish Early Accelerate Faster、Work Flows Inward 以及 Completion Headroom。
A team exhibits a high degree of Product Pride to pause in its work for the good of the product quality and reputation. Other related patterns include: Product Owner, Product Backlog, Teams That Finish Early Accelerate Faster, Work Flows Inward, and Completion Headroom.
[1] — . “The Tragedy of the Commons.ˮ Wikipedia, https://en.wikipedia.org/wiki/Tragedy_of_the_commons, June 2018 (accessed 6 June 2018).
Picture credits: Shutterstock.com.
這項 Scrum Pattern 的系列文：
- 化緊急為有序：Sprint緩衝區設計完整指南（一）：Scrum Pattern 的中英對照翻譯
- 化緊急為有序：Sprint緩衝區設計完整指南（二）：Scrum Pattern 的中英對照翻譯
- 我對「Illegitimus Non Interruptus」這項 Scrum Pattern 的想法：TBD
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