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Trends in Productivity and COCOMO Cost Drivers over the Years

Trends in Productivity and COCOMO Cost Drivers over the Years. Vu Nguyen Center for Systems and Software Engineering (CSSE) CSSE Annual Research Review 2010 Mar 9 th , 2010. Outline. Objectives and Background. Productivity Trend. Cost Driver Trends. Discussions and Conclusions.

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Trends in Productivity and COCOMO Cost Drivers over the Years

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  1. Trends in Productivity and COCOMO Cost Drivers over the Years Vu Nguyen Center for Systems and Software Engineering (CSSE) CSSE Annual Research Review 2010 Mar 9th, 2010

  2. Outline Objectives and Background Productivity Trend Cost Driver Trends Discussions and Conclusions

  3. Objectives • Analysis of Productivity • How the productivity of the COCOMO data projects has changed over the years • What caused the changes in productivity • Analysis of COCOMO cost drivers • How cost driver ratings have changed over the years • Are there any implications from these changes

  4. Estimation models need upgrading • It has been 10 years since the release of COCOMO II.2000 • Data collected during 1970 – 1999 • Software engineering practices and technologies are changing • Process: CMM  CMMI, ICM, agile methods • Tools are more sophisticated • Advanced communication facility • Improved storage and processing capability

  5. COCOMO II Formula • Effort estimate (PM) • COCOMO II 2000: A and B constants were calibrated using 161 data points with A = 2.94 and B = 0.91 • Productivity = • Constant A is considered as the inverse of adjusted productivity

  6. COCOMO Data Projects Over the Five-year Periods • Dataset has 341 projects completed between 1970 and 2009 • 161 used for calibrating COCOMO II 2000 • 149 completed since 2000

  7. Outline Objectives and Background Productivity Trend Cost Driver Trends Discussions and Conclusions

  8. Average productivity is increasing over the periods • Two productivity increasing trends exist: 1970 – 1994 and 1995 – 2009 • 1970-1999 productivity trends largely explained by cost drivers and scale factors • Post-2000 productivity trends not explained by cost drivers and scale factors KSLOC per PM 1970-1974 1975-1979 1985-1989 1990-1994 1995-1999 2000-2004 2005-2009 Five-year Periods

  9. EAF Sum of Scale Factors 1970- 1975- 1980- 1985- 1990- 1995- 2000- 2005- 1974 1979 1984 1989 1994 1999 2004 2009 1970- 1975- 1980- 1985- 1990- 1995- 2000- 2005- 1974 1979 1984 1989 1994 1999 2004 2009 Effort Multipliers and Scale Factors • EM’s and SF’s don’t change sharply as does the productivity over the periods Effort Adjustment Factor (EAF) or ∏EM Sum of Scale Factors (SF)

  10. Constant A generally decreases over the periods • Calibrate the constant A while stationing B = 0.91 • Constant A is the inverse of adjusted productivity • adjusts the productivity with SF’s and EM’s • Constant A decreases over the periods 50% decrease over the post-2000 period 1970- 1975- 1980- 1985- 1990- 1995- 2000- 2005- 1974 1979 1984 1989 1994 1999 2004 2009

  11. Outline Objectives and Background Productivity Trend Cost Driver Trends Discussions and Conclusions

  12. Correlation between cost drivers and completion years • Trends in cost drivers • Cost drivers unchanged • TEAM, FLEX, RESL, RELY, CPLX, ACAP, PCAP, RUSE, DOCU, PCON, SITE, SCED • Increasing trends: increasing effort • DATA, APEX • Decreasing trends: decreasing effort • PMAT, TOOL, PREC,TIME, STOR, PLEX, LTEX, PVOL

  13. Application and Platform Experience • Platform and language experience has increased while application experience decreased • Programmers might have moved projects more often in more recent years

  14. Use of Tools and Process Maturity • Use of Tools and Process Maturity have increased significantly

  15. Storage and Time Constraints • Storage and Time are less constrained than they were

  16. Outline Objectives and Background Productivity Trend Cost Driver Trends Discussions and Conclusions

  17. Discussions • Productivity has doubled over the last 40 years • But scale factors and effort multipliers did not fully characterize this increase • Hypotheses/questions for explanation • Is standard for rating personnel factors different among the organizations? • Were automatically translated code reported as new code? • Were reused code reported as new code? • Are the ranges of some cost drivers not large enough? • Improvement in tools (TOOL) only contributes to 20% reduction in effort • Are more lightweight projects being reported? • Documentation relative to life-cycle needs

  18. Conclusions • Productivity is generally increasing over the 40-year period • SF’s and EM’s only partially explain this improvement • Advancements in processes and technologies affect some cost drivers • But majority of the cost driver ratings are unchanged • Changes in productivity and cost drivers indicate that estimation models should recalibrate regularly

  19. Thank You

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