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Bottom-up time estimations techiques

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An overview of bottom-up time estimations techniques in project management. From Project Management Fundamentals, a new type of textbook designed to be: granular, easy to use with a "flipped" classroom approach, and designed for electronic distribution on iPads, kindle readers, and PCs/Mac. Find out more at http://pmf.education/

Published in: Engineering
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Bottom-up time estimations techiques

  1. 1. Bottom-Up (Micro) • Single-Point Estimation • Three-Point Estimates • Multiple Estimators • Delphi Technique
  2. 2. 1. Have people familiar with the tasks make the estimate. 2. Use several people to make estimates. 3. Base estimates on normal conditions, efficient methods, and a normal level of resources. 4. Use consistent time units in estimating task times. 5. Treat each task as independent, don’t aggregate. 6. Don’t make allowances for contingencies. 7. Adding a risk assessment helps avoid surprises to stakeholders. Estimating Guidelines for Times, 
 Costs, and Resources
  3. 3. Single Point Estimation 30 Days to Complete How long will Task A take to complete? Bottom-up (Micro)
  4. 4. Three-Point Estimates How long will Task A take to complete? Optimistic (a) 20 days Most Likely (m) 30 days Pessimistic (b) 58 days
  5. 5. Three-Point Estimates Optimistic (a) 20 days Most Likely (m) 30 days Pessimistic (b) 58 days How long will Task A take to complete? 20 Days + 30 Days + 58 Days 3 Estimates = 36 days Triangular Distribution or simple average
  6. 6. Activity Time Calculations weighted average activity time =Te
  7. 7. Activity Time Calculations Te a + 4m + b 6 =
  8. 8. Three-Point Estimates How long will Task A take to complete? te 20+ 4*30 + 58 6 = Optimistic (a) 20 days Most Likely (m) 30 days Pessimistic (b) 58 days
  9. 9. Three-Point Estimates How long will Task A take to complete? te = 33.00 days Optimistic (a) 20 days Most Likely (m) 30 days Pessimistic (b) 58 days
  10. 10. Beta Distribution Optimistic (a) LikelinessorProbability—> Most Likely (m) Pessimistic (b) te
  11. 11. Beta Distribution Optimistic (a) LikelinessorProbability—> Most Likely (m) Pessimistic (b) 33.00 days
  12. 12. Three-Point Estimates Estimated Project Duration: 243 days Probably that project will be done in 250 days: 74% PERT Analysis
  13. 13. Multiple Estimators Bottom Up Estimating Estimator 1 Estimator 2 Estimator 33 20 Days 30 Days 50 Days Bottom-up (Micro)
  14. 14. Multiple Estimators Bottom Up Estimating Estimator 1 Estimator 2 Estimator 33 20 Days 30 Days 50 Days Bottom-up (Micro)
  15. 15. Multiple Estimators Bottom Up Estimating 20 Days Estimator 1 Estimator 2 Estimator 33 20 Days + 30 Days + 50 Days 3 Estimators = 33.3 Days Bottom-up (Micro) 30 Days 50 Days
  16. 16. Delphi Technique
  17. 17. Multiple Estimators Estimator 1 Estimator 2 Estimator 3 30 days 3 Bottom-up (Micro)
  18. 18. Bottom-Up (Micro) • Single-Point Estimation • Three-Point Estimates • Multiple Estimators • Delphi Technique

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