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- 1. Estimating in Software Development:No Silver Bullets Allowed Kent J. McDonald @beyondreqs
- 2. Disclaimer
- 3. A Familiar Situation? Issues with Estimating Estimating Techniques
- 4. Don’t worry, we’ll get to these…
- 5. Has this ever happened to you?Ok, great. The Sales How long will it VP promised an I just found out take to build the estimate to the about it this commissionCEO next Monday. morning, so I’ll need system? It better be right. to do some analysis .
- 6. Issues with EstimatingInitial Uncertainty Accuracy/Effort TradeoffFalse Precision Differing Skill Levels
- 7. Initial Uncertainty
- 8. Cone of Uncertainty
- 9. Cone of Uncertainty a Practical Use
- 10. Hurricane Sandy – Actual Path
- 11. Accuracy/Effort Tradeoff
- 12. Point of Diminishing Returns
- 13. False Precision
- 14. How precise do you have to be? How long, and Approximately 374 how much? days and $2,548,931.27.
- 15. Differingskill levels
- 16. People finish tasks at different speeds
- 17. Estimating TechniquesGuestimate Break it down, add it up Relative Estimating
- 18. Guestimate
- 19. Aka “Gut Feel” or “Ball Park”How long, and how much? About a year and $2.5 million.
- 20. Comparison to Past Projects$1,000 $100K $10M ?? $1M
- 21. Your turn…Want to create an online application for Mortgage InsuranceHow long to deliver the onlineapplication for MortgageInsurance?A ballpark answer is sufficient.
- 22. Does it address our issues?Initial Uncertainty Accuracy/Effort TradeoffFalse Precision Differing Skill Levels
- 23. When to use it
- 24. Break it downAdd it up
- 25. Break overall effort into bits
- 26. Assign factor to each small bitTasks Time Factor # of Total Time (hour/bit) bits (hours)InterfacesGUI - Simple 8GUI - Medium 16GUI - Hard 24System Interface - Simple 12System Interface - Complex 30 Total InterfacesProcessesSimple Process 16Medium Process 32Complex Process 48 Total Processes
- 27. Where do we come up with the factors?
- 28. This is where time cards may be useful… Know ahead of time what you want to track Build up information over time Often requires excruciating detail in time collection.
- 29. Identify How Many BitsTasks Time Factor # of Total Time (hour/bit) bits (hours)InterfacesGUI - Simple 8 3GUI - Medium 16 2GUI - Hard 24 1System Interface - Simple 12 3System Interface - Complex 30 2 Total Interfaces 11ProcessesSimple Process 16 5Medium Process 32 4Complex Process 48 3 Total Processes 12
- 30. Do the math to get an estimateTasks Time Factor # of Total Time (hour/bit) bits (hours)InterfacesGUI - Simple 8 3 24GUI - Medium 16 2 32GUI - Hard 24 1 24System Interface - Simple 12 3 36System Interface - Complex 30 2 60 Total Interfaces 11 176ProcessesSimple Process 16 5 80Medium Process 32 4 128Complex Process 48 3 144 Total Processes 12 352
- 31. This gives us development hours
- 32. What about analysis & testing &… Percentage of development hours Estimate tasks separately You mean we have to estimate analysis & testing?
- 33. Data Warehouse ExampleAdding a new source todata warehouse Count of sources Count of tables/source Count of elements/table Considerations of complexity
- 34. Data Warehouse Example 1. Gather all the info 2. Plug it into a spreadsheet 3. Look at the resulting (realistic but “too high”) number 4. Revise…
- 35. Your turn…Want to create an online application for Mortgage InsuranceHow long to deliver the onlineapplication for MortgageInsurance?Identify how you would breakthis down to estimate
- 36. Of Course there’s always Function Points…
- 37. Or, you could always add up tasks
- 38. Does it address our issues?Initial Uncertainty Accuracy/Effort TradeoffFalse Precision Differing Skill Levels
- 39. When to use it
- 40. Another Look - Decomposition
- 41. Calibrated Estimates in Ranges Manage Moderate Manage Build Manage Tracks Content Deadlines Program Venue 1 – 2 Days 3 – 5 Days 1 – 2 Days 4 – 6 Days .5 – 1 Days 9.5 – 16 Days @ $100/hour & 8 hours/day $7,600 – $12,800Note, Entire team calibrated andinvolved in determining these estimates.
- 42. For More information How to Measure Anything: Finding the Value of Intangibles in Business by Douglas W. Hubbard HowToMeasureAnything.com
- 43. Where it HelpsInitial Uncertainty Accuracy/Effort TradeoffFalse Precision Differing Skill Levels
- 44. Relative Estimating
- 45. Ah ha! Here’s the poker connection!
- 46. Discuss (briefly) the item to estimate As an Event Organizer I want to know how audience members vote by athlete by gender So That I can determine if men and women vote differently.
- 47. The Delphi Technique
- 48. Everyone selects an estimate
- 49. Estimating Scales(Modified) FibonacciSequence:0, ½, 1, 2, 3, 5, 8, 13, 20,40, 80, 100Using a regular deck ofcards:A, 2, 3, 5, 8, KingTeam Member Hands:1–5 Leonardo Pisano Bigollo aka Fibonacci Italian Mathematician
- 50. Reveal estimates all at once
- 51. Discuss outliers Well, we changed the votingI wasn’t sure we knew howmachines to ask gender a Andwhy did youthe two So how about pick during Yeah, what she said. to tell an audience sign in last iteration, so it king? aces? member’s gender. should be easy
- 52. Repeat until convergence
- 53. Extrapolate based on Velocity Assumptions: 2 week iterations Overall backlog size: 600 points Planning Velocity: 30 5 Person Team Avg Cost/person/wk: $4,000 Estimate: $800,000
- 54. Your turn…Determine relative sizes of these variousfeatures using the scale 1,2,3,4,5Based on this feature being sized an 1.
- 55. Does it address our issues?Initial Uncertainty Accuracy/Effort TradeoffFalse Precision Differing Skill Levels
- 56. When to use it
- 57. An Alternative to Planning Poker 1 2 3 5 8User Story User Story User Story User StoryUser Story User Story User Story User StoryUser Story User StoryUser Story User Story
- 58. How should we approach estimating for a project?
- 59. CalibratedGuestimate Phase Based Estimates Break it down add it up Set expectation for revisions
- 60. AgileComparison Calibrated to past Estimates projects Extrapolate from Velocity Setexpectationfor revisions
- 61. If you remember nothing elseInitial Don’t spenduncertainty more effortmeans you will than it’snot be accurate. worth.Don’t imply Incorporatemore precision multiplethan is perspectives.possible.
- 62. Questions?Kent J. McDonaldkent@kentmcdonald.comwww.BeyondRequirements.comTwitter: @BeyondReqsSlides available from:http://www.knowledgebridgepartners.com/presentations/softwareestimating/ 65

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