1. Cost9a 1 Software Estimating Technology: A Survey Richard Stutzke Crosstalk, May96 text pp204-215

3. Cost9a 3 Cost Estimation An estimate of the effort and duration, associated costs of equipment, travel and training and the rationale for the calculations

4. Cost9a 4 Problem u “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.”

5. Cost9a 5 Recommendation u If you are involved with cost estimation, I recommend the following book u Tom DeMarco, Controlling Software Projects, Yourdon Press, NY c1982

6. Cost9a 6 Definition of Estimate (DeMarco) u Default: – "An estimate is the most optimistic prediction that has a non-zero probability of coming true" u Proposed: – "An estimate is a prediction that is equally likely to be above or below the actual result"

7. Cost9a 7 Estimates should not become goals u DeMarco argues that the estimation and the management decision about pricing or goals should be separate.

8. Cost9a 8 Estimate

9. Cost9a 9 Parametric Cost Estimation u LOC models – Boehm's COCOMO – Putnam's Model (SLIM) u non-LOC models – Function Points u combination – COCOMO2

10. Cost9a 10 Prediction Formulas E=  X   >1  <1

11. Cost9a 11 Boehm's COCOMO u Software Engineering Economics – article (1983) pp216-233 in text u Software Engineering Economics – (book) Prentice-Hall c1981 u type COCOMO in a search engine - many www sites

12. Cost9a 12 COnstructive COst MOdel u Basic – macro - overview of whole project with one metric of KSLOC u Intermediate – multiplicative adjustment factors u Detailed – applying model to each phase

13. Cost9a 13 Modes of Software Development u Organic – detached, often batch u Semidetached – e.g. transaction processing u Embedded – e.g. os kernel

14. Cost9a 14 Programmer Effort u Application Programs – PM = 2.4 * (KDSI) 1.05 u Utility Programs – PM = 3.0 * (KDSI) 1.12 u Systems Programs – PM = 3.6 * (KDSI) 1.20 Note A’s in text are different from later versions of COCOMO

15. Cost9a 15 Example for effort u Size Appl Util Sys u 5K 13.0 18.2 24.8 u 10K 26.9 39.5 57.1 u 15K 41.2 62.2 92.8 u 20K 55.8 86.0 131.1 u 25K 70.5 110.4 171.3 u 30K 85.3 135.3 213.2 u 35K 100.3 160.8 256.6 u 40K 115.4 186.8 301.1 u 45K 130.6 213.2 346.9 u 50K 145.9 239.9 393.6

16. Cost9a 16 Development Time (Months) u Application Programs – TDEV = 2.5 * (PM) 0.38 u Utility Programs – TDEV = 2.5 * (PM) 0.35 u Systems Programs – TDEV = 2.5 * (PM) 0.32

17. Cost9a 17 Example for development time u size appl util sys u 5K 6.63 6.90 6.99 u 10K 8.74 9.06 9.12 u 15K 10.27 10.62 10.66 u 20K 11.52 11.88 11.90 u 25K 12.60 12.97 12.96 u 30K 13.55 13.93 13.91 u 35K 14.40 14.80 14.75 u 40K 15.19 15.59 15.53 u 45K 15.92 16.33 16.25 u 50K 16.61 17.02 16.92

18. Cost9a 18 Average Staffing Levels u Calculate by dividing PM by TDEV

19. Cost9a 19 Example for staffing levels u size appl util sys u 5K 1.96 2.63 3.55 u 10K 3.08 4.37 6.26 u 15K 4.01 5.87 8.71 u 20K 4.84 7.23 11.02 u 25K 5.60 8.51 13.21 u 30K 6.30 9.72 15.33 u 35K 6.97 10.87 17.39 u 40K 7.60 11.98 19.39 u 45K 8.20 13.05 21.35 u 50K 8.79 14.09 23.27

20. Cost9a 20 COCOMO Effort Multipliers u product attributes – required reliability 0.75 - 1.40 – data-base size 0.94 - 1.16 – product complexity 0.70 - 1.65 u 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

21. Cost9a 21 The Cocomo 2.0 Software Cost Estimation Model Barry Boehm, etal See web pages