Critical Estimation Concepts Chapter3
- 1. Software Costing and Estimation Critical Estimation Concepts Chapter 3: Value of Accurate Estimates Mohammad Ayub Latif Head ISG and Asst. Prof. CS
- 2. Is it better to overestimate or underestimate Accurate estimates are rare, so if we are going to err, is it better to err on the side of overestimation or underestimation?
- 3. Arguments against over estimation If project is over estimated , Parkinson’s Law will kick in; Parkinson’s Law is the based on the idea that work will expand to fill the available gap; Most managers consciously squeeze the estimates to try to avoid Parkinson’s Law.
- 5. Arguments against underestimation Underestimation creates numerous problems: Reduces effectiveness of project plans Statistically reduced chance of on time completion Poor technical foundation leads to worse than nominal results Destructive late project dynamics make the project worst than nominal
- 6. Weighing the Arguments Tip Don’t intentionally underestimate; the penalty of underestimation is more severe than overestimation. Address concerns about overestimation through planning and control, not by biasing your estimates
- 7. Software Industry track record The Standish Group has published a biennial survey called “The Chaos Report” which describes software project outcome. In 2004 54% project were delivered late 18% failed outright 28% were delivered on time and within budget
- 8. Software Industry track record
- 9. Software Industry track record by Caper Jones
- 11. Benefits of accurate estimates Improved status visibility Higher Quality Better coordination with non software functions Better Budgeting Increased credibility for the development team Early Risk Information Tip Recognize a mismatch between a project’s business target and objective for what it is: valuable risk information that the project might not be successful . Take corrective action early, when it can do some good.
- 12. Value of predictability compared with other desirable project outcomes Some of the goals, software strive for: Schedule Cost Functionality What is important, the ability to change your mind about features, or the ability to know cost, schedule and functionality in advance? Majority project managers will opt for the later option. Everyone wants predictability.
- 14. Value of predictability Tip: Many businesses value predictability more than development time, cost or flexibility. Be sure you understand what your business values the most.