Bucket System Estimation technique is used when there is a very large numbers of items to be estimated with a medium to big sized group of people, and to do it quickly. This approach provides a consistent way for teams to size stories by discussing each story in terms of pre-defined buckets of complexity before deciding on the final points. Benefits of Bucket System Estimation are Fast, Collaborative, Relative Estimate, Group Accountability & Works with teams to estimate effort or with stakeholders to estimate value.

Bucket System

Buckets: 0,1,2,3,4,5,8,13,20,30,50,100, and 200, I would recommend to use fibonacci series and use up tp 21 story points.

Bucket Estimation Execution

  1. Always estimate stories against each other, not individually. Select sticky notes with numbers which are applicable to your team e.g. 1,2,3,5,8,13 and 21. Paste in sequence on a table or white board. Every section belonging to at least one user story is called a bucket.
  2. Pick a story that feels smallish (but not the smallest) and call it a 2. Another variation is to choose an story at random from the collection.  Read it to the group.  Place it in the mid point bucket e.g. “8” bucket.  This item is our first reference item.
  3. Pick next two stories & relatively size each story against the reference story, consider the details that affect its size. Capture all assumptions. Get this exercise for at least 3 stories. For example 
  • User Interface: Number of screen fields, Screen validation logic and Number of screens.
  • Business Logic: Number of business rules and Business Rule complexity
  • Data / Integration: Number of data stores, Complexity of StoredProc and Number of tables 
  • Testing: User testing complexity, Data setup complexity and Test automation 
  1. Once consensus has been reached, put each story into a bucket 1,2,3,5,8,13 and 21, I recommend to use Fibonacci series for ease of planning.
  2. If the random items have clearly skewed the scale towards one end or the other, re-scale the items (e.g. if the first item is actually very small and should be in the “1” bucket). The baseline can be changed. If participants think that the baseline story is mere 5 and not 8, then they can change that.The buckets can also be changed and rearranged if the group feels it necessary to reassign an item. 
  3. After at least three stories are bucketed, distribute remaining items among all participants and without any discussion every participant places its story in the bucket he sees correct/fit for their story. This step is called “Divide & Conquer” approach.
  4. If a participant does not understand a story, it can be transferred or exchanged with someone else story. 
  5. Try to keep your story size small. Ideally an 8 should be able to be delivered in one iteration. Anything bigger, and it’s best to use an “epic” to indicate that it needs to be broken down. 
  6. For each story bucket, do a quick review of the stories in them and their estimates. Are they all reasonably close in “size” to each other? Shift buckets if required. ‘sanity check’ is critical to this process. 
  7. Write the bucket numbers on the cards so that the estimates are recorded. Then work out your current understood scope just by adding up the numbers.

What if we have a very big story e.g. 200 story points? 

It goes into the 21 Bucket. The 21 bucket is also a catch-all bucket for stories too big or too poorly understood to estimate. 

Bucket System Estimation using Complexity

This approach provides a consistent way for teams to size stories by discussing each story in terms of pre-defined buckets of complexity before deciding on the final points. 

  • Decide on the buckets of complexity you think match your project & paste in sequence. 
  • Discuss the story in each bucket and determine if the team can agree if the work it has a Light, Medium, High or Complex level of complexity. 
  • Add up the points and see which Fibonacci Story Point bucket it falls into. If it falls between two buckets, have the team do a gut check and decide on which ones it falls into.
1 - Smallest
2 - Small
3 - Medium
5 - Med-Large
8 - Large
13 - Very Large
21 - EPIC

Summary

Bucket System is a good alternative to Planning Poker as it is time efficient and provides reasonable results.It is a great agile estimation technique to use if you have a large number of items and a big team.

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