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COCOMO II Calibration Status

COCOMO II Calibration Status. COCOMO Forum October 2004. A Little History. Calibration effort started in January 2002 Confusion Repository in an inconsistent state “Uncharacterized” data from many sources Process for duplicating the 2000 calibration results

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COCOMO II Calibration Status

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  1. COCOMO II Calibration Status COCOMO Forum October 2004

  2. A Little History • Calibration effort started in January 2002 • Confusion • Repository in an inconsistent state • “Uncharacterized” data from many sources • Process for duplicating the 2000 calibration results • Schedule compression rating was inconsistent • Expectation • New data had a lot of variation but… • Affiliates (and the user population in general) want an “Accurate” and up-to-date model – not just one that explained variation • PRED(.25) versus R2 COCOMO Forum - October 2004

  3. Change in Approach • Removed pre-1990 data from dataset used in calibration • This removed a lot of “converted” data • Removed “bad” data • Incomplete: No duration data, estimated effort, no valid SLOC size • Still use the Bayesian calibration approach developed by Chulani • Changed to a holistic analysis approach: considered effort and duration together • Identified data that needed review • Schedule compression was automatically set COCOMO Forum - October 2004

  4. Post-1989 Data Using Current COCOMO II Values Effort Underestimated Duration Overestimated Effort Overestimated Duration Overestimated Effort Overestimated Duration Underestimated Effort Underestimated Duration Underestimated COCOMO Forum - October 2004

  5. Effort- Duration Error Interpretation COCOMO Forum - October 2004

  6. Effort Estimate Error Compared to Size (Post 1989 – 89 Projects, 2000 Cal) COCOMO Forum - October 2004

  7. Duration Estimate Error Compared to Size (Post 1989 – 89 Projects, 2000 Cal) COCOMO Forum - October 2004

  8. Accuracy Results Effort Estimation Accuracy Duration Estimation Accuracy COCOMO Forum - October 2004

  9. Calibration Progress • Reviewing new data • Dataset A: 8 projects • Dataset B: 52 projects • Dataset C: 13 projects • Dataset D: 4 projects • Dataset E: 10 projects • Dataset F: 8 projects COCOMO Forum - October 2004

  10. Dataset A Effort Underestimated Duration Overestimated Effort Overestimated Duration Overestimated Effort Underestimated Duration Underestimated Effort Overestimated Duration Underestimated COCOMO Forum - October 2004

  11. Dataset B Effort Overestimated Duration Overestimated Effort Underestimated Duration Overestimated Effort Underestimated Duration Underestimated Effort Overestimated Duration Underestimated COCOMO Forum - October 2004

  12. Dataset C Effort Underestimated Duration Overestimated Effort Overestimated Duration Overestimated Effort Underestimated Duration Underestimated Effort Overestimated Duration Underestimated COCOMO Forum - October 2004

  13. Dataset D & E Effort Underestimated Duration Overestimated Effort Overestimated Duration Overestimated Effort Overestimated Duration Underestimated COCOMO Forum - October 2004

  14. Dataset F Effort Underestimated Duration Overestimated Effort Overestimated Duration Overestimated Effort Underestimated Duration Underestimated Effort Overestimated Duration Underestimated COCOMO Forum - October 2004

  15. Observations on New Data • The estimation error of the new datasets lie outside the Post-1989 (Cal 2000) dataset error range • When each dataset is given its own (local) calibration constant, A, accuracy improves • There have been some suggestions on modifying the COCOMO II model • “Globbing” data by application domain or platform and provide different model constants for each “glob” • Add a Cost Driver that accounts for “spread” of data COCOMO Forum - October 2004

  16. Proposed New Driver • Domain Expertise Driver • Definition: • Cumulative knowledge and experience that has been acquired through a thorough track record that comes to represent the core competencies of an organization COCOMO Forum - October 2004

  17. Next Steps • Finish Early COCOTS calibration • Tailoring and Glue Code activities to analyze • Model definition manual and tool • Finish COCOMO II calibration • Consider “Globbing” over adding a new driver • Start COCOMO II Driver Elaboration • Make some driver descriptions less subjective • Crisper definitions COCOMO Forum - October 2004

  18. For more information, requests or questions Brad Clark Software Metrics, Inc. brad@software-metrics.com Ye Yang USC-CSE yey@usc.edu COCOMO Forum - October 2004

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