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Building a more accurate burndown   Using Range Estimation in Scrum Agile 2010 Conference August 2010 Arin Sime 434 996 52...
Pitfalls of traditional estimation techniques
How long does it take you to get to work? traffic optimistic every day? method of travel
68% <ul><ul><li>http://www1.standishgroup.com/newsroom/chaos_2009.php </li></ul></ul>
A little about me… <ul><li>Senior Consultant, OpenSource Connections in Charlottesville, Virginia </li></ul><ul><li>Master...
The root of all estimation evil:  Single point estimates <ul><ul><li>Chart taken from:  Software Estimation , Steve McConn...
A realistic estimate distribution <ul><ul><li>Chart taken from:  Software Estimation , Steve McConnell, Figure 1-3, p8 </l...
Reasons we are wrong so often <ul><li>Different information </li></ul><ul><li>Different methods </li></ul><ul><li>Psycholo...
Bias in Estimation <ul><li>Imagine this scenario: </li></ul><ul><li>“ Can you build me that CMS website in 2 weeks?” </li>...
Bias in Estimation <ul><li>By supplying my own estimate (or desire) in my question, I have anchored your response. </li></...
You’re not as good as you think <ul><li>“ The Expert Problem” </li></ul><ul><li>Experts consistently underestimate their m...
The best protection <ul><li>“ The best protection against all psychological traps – in isolation or in combination – is aw...
Agile estimation techniques
How agile already avoids pitfalls <ul><ul><li>Encourages team airing of estimates </li></ul></ul><ul><ul><li>Done before a...
How agile already avoids pitfalls <ul><ul><li>Separates story from time units, more relative </li></ul></ul>Story Points &...
Agile and Scrum can run into other pitfalls though…
Potential pitfalls: Single-point estimates What about Risk? Implies a set delivery of features Story points are hard to ex...
Better accuracy using range estimation
The Cone of Uncertainty <ul><ul><li>http://www.construx.com/Page.aspx?hid=1648 </li></ul></ul>
Range estimation … <ul><li>Recognizes uncertainty </li></ul><ul><li>Alleviates our tendency towards optimism </li></ul><ul...
Incorporating range estimation into Scrum
Incorporating range estimation into Scrum <ul><li>Team originally estimated 108 hours </li></ul><ul><li>Range estimate wen...
Range estimation in Scrum Poker <ul><li>It’s very simple – just hold two cards instead of one! </li></ul><ul><li>The same ...
<ul><li>On the high end </li></ul>Range estimation in Scrum Poker On the low end On the high end The likely discussion: He...
Range estimation in Scrum Poker Still middle of the road, but Green recognizes some risk Orange sees this as really easy  ...
Using ranges in your task list
Using ranges in your task list Enter Low/High =(Lo*0.33)+(Hi*0.67) Sums of Lo, Hi, 2/3; then trend them to zero update daily
Using ranges in your burndown
Ranges help to highlight obstacles and know when to cancel an iteration
We were able to improve on the next iteration, but it was still hard
Ranges help reinforce obstacles Obstacle removed
Why 2/3? <ul><li>Because it is both simple and pessimistic </li></ul><ul><li>PERT does a similar thing: </li></ul><ul><li>...
Using ranges to better communicate
Using range estimation to communicate risk <ul><li>Size of your range communicates the risk of your task </li></ul><ul><li...
How long? Um… 2 days 4 days Do you know your fudge factor? You Your Boss Big Boss
How long? 2-4 days 2-4 days Ranges help you control your fudge factor You Your Boss Big Boss
Another example:  Use ranges to better empower your boss or client You Your Boss Big Boss
Perfect – Do it! How long? How much for X? GRRR Umm….. You Your Boss Big Boss 2 days Actually … 4 days 4 days later… 2 day...
Instead…. You Your Boss Big Boss
No thx, do something easier How long? How much for X? YES! You Your Boss Big Boss 2-4 days Done! 2 days later… 2-4 days * ...
Potential pitfalls of range estimation
Potential pitfalls of range estimation Really Wide Ranges Not everything can take  2 – 200 hours or you lose all credibility
Potential pitfalls of range estimation Bosses who don’t get it You’re going to have to sell them on how your estimates wil...
Potential pitfalls of range estimation Pushed back deadlines Ranges are not an excuse to always miss deadlines.  But they ...
Potential pitfalls of range estimation Is 2/3 the new single-point? Be careful not to just start treating the 2/3 calculat...
Further Reading
Questions? Arin Sime 434 996 5226 [email_address] Twitter.com/ArinSime
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Range estimation in Scrum

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Presentation by OpenSource Connections consultant Arin Sime at Agile2010 conference on how to incorporate range estimation techniques into Scrum.

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Range estimation in Scrum

  1. 1. Building a more accurate burndown Using Range Estimation in Scrum Agile 2010 Conference August 2010 Arin Sime 434 996 5226 [email_address]
  2. 2. Pitfalls of traditional estimation techniques
  3. 3. How long does it take you to get to work? traffic optimistic every day? method of travel
  4. 4. 68% <ul><ul><li>http://www1.standishgroup.com/newsroom/chaos_2009.php </li></ul></ul>
  5. 5. A little about me… <ul><li>Senior Consultant, OpenSource Connections in Charlottesville, Virginia </li></ul><ul><li>Masters in Management of I.T., University of Virginia, McIntire School of Commerce </li></ul><ul><li>We tweaked our Scrum process to incorporate Range Estimation based on my studies at Uva </li></ul><ul><li>Please take the Estimation Survey: http://www.surveymonkey.com/s/SWNNYQJ </li></ul>
  6. 6. The root of all estimation evil: Single point estimates <ul><ul><li>Chart taken from: Software Estimation , Steve McConnell, Figure 1-1, p6 </li></ul></ul>“ A single-point estimate is usually a target masquerading as an estimate.” -Steve McConnell
  7. 7. A realistic estimate distribution <ul><ul><li>Chart taken from: Software Estimation , Steve McConnell, Figure 1-3, p8 </li></ul></ul>“ There is a limit to how well a project can go but no limit to how many problems can occur.” -Steve McConnell Nominal Outcome (50/50 estimate)
  8. 8. Reasons we are wrong so often <ul><li>Different information </li></ul><ul><li>Different methods </li></ul><ul><li>Psychological Biases </li></ul><ul><li>The Expert Problem </li></ul>
  9. 9. Bias in Estimation <ul><li>Imagine this scenario: </li></ul><ul><li>“ Can you build me that CMS website in 2 weeks?” </li></ul><ul><li>How would you respond? </li></ul><ul><li>What estimate would you give? </li></ul>
  10. 10. Bias in Estimation <ul><li>By supplying my own estimate (or desire) in my question, I have anchored your response. </li></ul><ul><li>This is called “The anchoring or framing trap” </li></ul><ul><li>“ Because anchors can establish the terms on which a decision will be made, they are often used as a bargaining tactic by savvy negotiators.” </li></ul><ul><li>From “The Hidden Traps in Decision Making” from Harvard Business Review, 1998, John Hammond, Ralph L. Keeney, and Howard Raiffa </li></ul>
  11. 11. You’re not as good as you think <ul><li>“ The Expert Problem” </li></ul><ul><li>Experts consistently underestimate their margins of error, and discount the reasons they were wrong in the past. </li></ul><ul><li>Excuses for past mistakes: </li></ul><ul><li>You were playing a different game </li></ul><ul><li>Invoke the outlier </li></ul><ul><li>“ Almost right” defense </li></ul><ul><ul><li>The Black Swan: The impact of the Highly Improbable , </li></ul></ul><ul><ul><li>by Nassim Nicholas Taleb, 2007, Chapter 10: The Scandal of Prediction </li></ul></ul>
  12. 12. The best protection <ul><li>“ The best protection against all psychological traps – in isolation or in combination – is awareness.” </li></ul><ul><li>From “The Hidden Traps in Decision Making” from Harvard Business Review, 1998, John Hammond, Ralph L. Keeney, and Howard Raiffa </li></ul>
  13. 13. Agile estimation techniques
  14. 14. How agile already avoids pitfalls <ul><ul><li>Encourages team airing of estimates </li></ul></ul><ul><ul><li>Done before assignment of tasks </li></ul></ul>Scrum poker
  15. 15. How agile already avoids pitfalls <ul><ul><li>Separates story from time units, more relative </li></ul></ul>Story Points & Velocity <ul><ul><li>Image from: http://leadinganswers.typepad.com/leading_answers/2007/09/agile-exception.html </li></ul></ul>
  16. 16. Agile and Scrum can run into other pitfalls though…
  17. 17. Potential pitfalls: Single-point estimates What about Risk? Implies a set delivery of features Story points are hard to explain
  18. 18. Better accuracy using range estimation
  19. 19. The Cone of Uncertainty <ul><ul><li>http://www.construx.com/Page.aspx?hid=1648 </li></ul></ul>
  20. 20. Range estimation … <ul><li>Recognizes uncertainty </li></ul><ul><li>Alleviates our tendency towards optimism </li></ul><ul><li>Incorporates risk </li></ul><ul><li>Allows for better financial projections </li></ul><ul><li>Better informs our bosses and clients </li></ul>
  21. 21. Incorporating range estimation into Scrum
  22. 22. Incorporating range estimation into Scrum <ul><li>Team originally estimated 108 hours </li></ul><ul><li>Range estimate went from 114-245 hours. </li></ul><ul><li>Note the single point was a low estimate! </li></ul><ul><li>They were able to finish original tasks a little early </li></ul>
  23. 23. Range estimation in Scrum Poker <ul><li>It’s very simple – just hold two cards instead of one! </li></ul><ul><li>The same rules apply about creating discussion between low and high estimators, but you might resolve them differently... </li></ul>
  24. 24. <ul><li>On the high end </li></ul>Range estimation in Scrum Poker On the low end On the high end The likely discussion: Hey Orange, why do you say “2”? Yellow and Blue both say “5”. Likely Outcome: 3 or 5 Middle of the road
  25. 25. Range estimation in Scrum Poker Still middle of the road, but Green recognizes some risk Orange sees this as really easy Blue sees this as more complicated The likely discussion: Orange and Blue need to compare their visions for this task. Likely Outcome: 8-13? Red and Blue no longer agree: Red is confused or sees big risks
  26. 26. Using ranges in your task list
  27. 27. Using ranges in your task list Enter Low/High =(Lo*0.33)+(Hi*0.67) Sums of Lo, Hi, 2/3; then trend them to zero update daily
  28. 28. Using ranges in your burndown
  29. 29. Ranges help to highlight obstacles and know when to cancel an iteration
  30. 30. We were able to improve on the next iteration, but it was still hard
  31. 31. Ranges help reinforce obstacles Obstacle removed
  32. 32. Why 2/3? <ul><li>Because it is both simple and pessimistic </li></ul><ul><li>PERT does a similar thing: </li></ul><ul><li>Expected = [BestCase + (4*MostLikely) + WorstCase] / 6 </li></ul><ul><ul><li>Source on PERT: Software Estimation , Steve McConnell, p109 </li></ul></ul>
  33. 33. Using ranges to better communicate
  34. 34. Using range estimation to communicate risk <ul><li>Size of your range communicates the risk of your task </li></ul><ul><li>May encourage you to break up tasks, or better define them. </li></ul><ul><li>Scrum is all about better communication with the customer – so are ranges </li></ul>
  35. 35. How long? Um… 2 days 4 days Do you know your fudge factor? You Your Boss Big Boss
  36. 36. How long? 2-4 days 2-4 days Ranges help you control your fudge factor You Your Boss Big Boss
  37. 37. Another example: Use ranges to better empower your boss or client You Your Boss Big Boss
  38. 38. Perfect – Do it! How long? How much for X? GRRR Umm….. You Your Boss Big Boss 2 days Actually … 4 days 4 days later… 2 days * rate Budget Left: 2 days
  39. 39. Instead…. You Your Boss Big Boss
  40. 40. No thx, do something easier How long? How much for X? YES! You Your Boss Big Boss 2-4 days Done! 2 days later… 2-4 days * rate Budget Left: 2 days
  41. 41. Potential pitfalls of range estimation
  42. 42. Potential pitfalls of range estimation Really Wide Ranges Not everything can take 2 – 200 hours or you lose all credibility
  43. 43. Potential pitfalls of range estimation Bosses who don’t get it You’re going to have to sell them on how your estimates will improve their decision making ability.
  44. 44. Potential pitfalls of range estimation Pushed back deadlines Ranges are not an excuse to always miss deadlines. But they do make it less of a surprise, and encourage you to be more cautious.
  45. 45. Potential pitfalls of range estimation Is 2/3 the new single-point? Be careful not to just start treating the 2/3 calculated estimate, use the ranges.
  46. 46. Further Reading
  47. 47. Questions? Arin Sime 434 996 5226 [email_address] Twitter.com/ArinSime

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