Chapter05

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Chapter05

  1. 1. Supplementary Slides for Software Engineering: A Practitioners Approach, 5/ e copyright © 1996, 2001 R.S. Pressman & Associates, Inc. For University Use Only May be reproduced ONLY for student use at the university levelwhen used in conjunction with Software Engineering: A Practitioners Approach. Any other reproduction or use is expressly prohibited. This presentation, slides, or hardcopy may NOT be used for short courses, industry seminars, or consulting purposes. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 1
  2. 2. Chapter 5 Software Project PlanningThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 2
  3. 3. Software Project Planning The overall goal of project planning is to establish a pragmatic strategy for controlling, tracking, and monitoring a complex technical project. Why? So the end result gets done on time, with quality!These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 3
  4. 4. The Steps t Scoping—understand the problem and the work that must be done t Estimation—how much effort? how much time? t Risk—what can go wrong? how can we avoid it? what can we do about it? t Schedule—how do we allocate resources along the timeline? what are the milestones? t Control strategy—how do we control quality? how do we control change?These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 4
  5. 5. Write it Down! Project Scope Software Estimates Project Risks Plan Schedule Control strategyThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 5
  6. 6. To Understand Scope ... t Understand the customers needs t understand the business context t understand the project boundaries t understand the customer’s motivation t understand the likely paths for change t understand that ... Even when you understand, nothing is guaranteed!These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 6
  7. 7. Cost Estimation project scope must be explicitly defined task and/or functional decomposition is necessary historical measures (metrics) are very helpful at least two different techniques should be used remember that uncertainty is inherentThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 7
  8. 8. Estimation Techniques t past (similar) project experience t conventional estimation techniques ¶ task breakdown and effort estimates ¶ size (e.g., FP) estimates t tools (e.g., Checkpoint)These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 8
  9. 9. Functional Decomposition Stateme functional perform of Scope nt a decomposition "grammatical parse"These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 9
  10. 10. Creating a Task Matrix Obtained from “process framework” framework activities application Effort required to functions accomplish each framework activity for each application functionThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 10
  11. 11. Conventional Methods: LOC/FP Approach t compute LOC/FP using estimates of information domain values t use historical effort for the projectThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 11
  12. 12. Example: LOC ApproachThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 12
  13. 13. Example: FP ApproachThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 13
  14. 14. Tool-Based Estimationproject characteristics calibration factors LOC/FP data These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 14
  15. 15. Empirical Estimation Models General form: exponent effort = tuning coefficient * size usually derived as person-months empirically of effort required derived usually LOC but may also be function point either a constant or a number derived based on complexity of projectThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 15
  16. 16. Estimation Guidelines estimate using at least two techniques get estimates from independent sources avoid over-optimism, assume difficulties youve arrived at an estimate, sleep on it adjust for the people wholl be doing the job—they have the highest impactThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 16
  17. 17. The Make-Buy Decision simple (0.30) $380,000 $450,000 difficult (0.70) build $275,000 minor changes (0.40) reuse system X $310,000 simple (0.20) major changes buy (0.60) $490,000 complex (0.80) minor changes $210,000 contract (0.70) $400,000 major changes (0.30) without changes (0.60) $350,000 $500,000 with changes (0.40)These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 17
  18. 18. Computing Expected Cost expected cost = (path probability) x (estimated path cost) i iFor example, the expected cost to build is: expected cost build= = 0.30($380K)+0.70($450K) = $429 K similarly,expected cost reuse = $382Kexpected cost buy = $267Kexpected cost contr = $410KThese courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach,5/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001 18

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