1 / 20

Software Estimating Technology: A Survey

Software Estimating Technology: A Survey. Richard Stutzke Crosstalk, May96 text pp204-215. Cost Estimation. An estimate of the effort and duration, associated costs of equipment, travel and training and the rationale for the calculations. Problem.

jherzog
Télécharger la présentation

Software Estimating Technology: A Survey

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Software Estimating Technology:A Survey Richard Stutzke Crosstalk, May96 text pp204-215

  2. Cost Estimation An estimate of the effort and duration, associated costs of equipment, travel and training and the rationale for the calculations

  3. Problem • “The estimator must estimate the effort (person-hours) and duration (calendar-day) for the project to enable managers to determine improtant business measures such as product costs, return on investment, and time to market.”

  4. Recommendation • If you are involved with cost estimation, I recommend the following book • Tom DeMarco, Controlling Software Projects, Yourdon Press, NY c1982

  5. Definition of Estimate (DeMarco) • Default: • "An estimate is the most optimistic prediction that has a non-zero probability of coming true" • Proposed: • "An estimate is a prediction that is equally likely to be above or below the actual result"

  6. Estimates should not become goals • DeMarco argues that the estimation and the management decision about pricing or goals should be separate.

  7. Estimate

  8. Parametric Cost Estimation • LOC models • Boehm's COCOMO • Putnam's Model (SLIM) • non-LOC models • Function Points • combination • COCOMO2

  9. Prediction Formulas b>1 E=aXb b<1

  10. Boehm's COCOMO • Software Engineering Economics – article (1983) pp216-233 in text • Software Engineering Economics – (book) Prentice-Hall c1981 • type COCOMO in a search engine - many www sites

  11. COnstructive COst MOdel • Basic • macro - overview of whole project with one metric of KSLOC • Intermediate • multiplicative adjustment factors • Detailed • applying model to each phase

  12. Modes of Software Development • Organic • detached, often batch • Semidetached • e.g. transaction processing • Embedded • e.g. os kernel

  13. Programmer Effort • Application Programs • PM = 2.4 * (KDSI)1.05 • Utility Programs • PM = 3.0 * (KDSI)1.12 • Systems Programs • PM = 3.6 * (KDSI)1.20 Note A’s in text are different from later versions of COCOMO

  14. Example for effort • Size Appl Util Sys • 5K 13.0 18.2 24.8 • 10K 26.9 39.5 57.1 • 15K 41.2 62.2 92.8 • 20K 55.8 86.0 131.1 • 25K 70.5 110.4 171.3 • 30K 85.3 135.3 213.2 • 35K 100.3 160.8 256.6 • 40K 115.4 186.8 301.1 • 45K 130.6 213.2 346.9 • 50K 145.9 239.9 393.6

  15. Development Time (Months) • Application Programs • TDEV = 2.5 * (PM) 0.38 • Utility Programs • TDEV = 2.5 * (PM) 0.35 • Systems Programs • TDEV = 2.5 * (PM) 0.32

  16. Example for development time • size appl util sys • 5K 6.63 6.90 6.99 • 10K 8.74 9.06 9.12 • 15K 10.27 10.62 10.66 • 20K 11.52 11.88 11.90 • 25K 12.60 12.97 12.96 • 30K 13.55 13.93 13.91 • 35K 14.40 14.80 14.75 • 40K 15.19 15.59 15.53 • 45K 15.92 16.33 16.25 • 50K 16.61 17.02 16.92

  17. Average Staffing Levels • Calculate by dividing PM by TDEV

  18. Example for staffing levels • size appl util sys • 5K 1.96 2.63 3.55 • 10K 3.08 4.37 6.26 • 15K 4.01 5.87 8.71 • 20K 4.84 7.23 11.02 • 25K 5.60 8.51 13.21 • 30K 6.30 9.72 15.33 • 35K 6.97 10.87 17.39 • 40K 7.60 11.98 19.39 • 45K 8.20 13.05 21.35 • 50K 8.79 14.09 23.27

  19. COCOMO Effort Multipliers • product attributes • required reliability 0.75 - 1.40 • data-base size 0.94 - 1.16 • product complexity 0.70 - 1.65 • computer attributes • execution time constraint 1.00 - 1.66 • main storage constraint 1.00 - 1.56 • virtual machine volatility 0.87 - 1.30 • computer turnaround time 0.87 - 1.15

  20. The Cocomo 2.0 Software Cost Estimation Model Barry Boehm, etal See web pages

More Related