Cocomo model scale factors software#
“In architecting a new software program, all the serious mistakes are made on the first day.” Robert Spinrad, VP-Xerox, 1988 “If you don’t actively attack the risks, the risks will actively attack you.” Tom Gilb, 1988 DBMS software loses derived data ġ0 Risk Exposure Factors and Contours: Satellite Experiment Softwareġ1 Risk Reduction Leverage (RRL) Equivalent to Return on InvestmentīEFORE - AFTER RRL = RISK REDUCTION COST Spacecraft Example LONG DURATION TEST FAILURE MODE TESTS LOSS (UO) PROB (UO) RE $20M 0.2 $4M $20M 0.2 $4M B B PROB (UO) RE 0.05 $1M 0.07 $1.4M A A COST $2M $0.26M 4-1 4- 1.4 = 1.5 = 10 RRL 2 0.26 ġ2 Outline What is Software Risk Management? When should you do it? Poor user interface causes inefficient operation I. Data reduction software errors cause extra work H. Hardware delay causes schedule overrun G. Monitoring software reports safe condition as unsafe F. Monitoring software reports unsafe condition as safe E. Fault tolerance features cause unacceptable performance D. High Check Utility - Loss Estimate Major Risk Risk Probability Check Probability Estimate Little Risk Low Loss of Utility Low High ĩ Risk Exposure Factors (Satellite Experiment Software) Risk Exposure RE = Prob (Loss) * Size (Loss) “Loss” – of stakeholders’ value financial reputation quality of service, … For multiple sources of loss: RE = source sources Ĩ Prioritizing Risks: Risk Exposure Risk Exposure = (Probability) (Loss of Utility) TRW Project B 1005 SPR’s 100 90 80 TRW Project A 373 SPR’s 70 % of Cost to Fix SPR’s 60 50 Major Rework Sources: Off-Nominal Architecture-Breakers A - Network Failover B - Extra-Long Messages 40 30 20 10 10 20 30 40 50 60 70 80 90 100 % of Software Problem Reports (SPR’s) Ħ Risk of Delaying Risk Management: Systemsīlanchard- Fabrycky, 1998 (Cone of Uncertainty)
Cocomo model scale factors code#
1 Software Risk Management and the COCOMO ModelĢ Outline What is Software Risk Management? When should you do it?Ĭontinuously from Day One How should you do it? Risk Assessment Cost risk assessment and COCOMO II Risk Control Conclusions Īn approach for early identification and mitigation of critical project uncertainties Learning early and cheaply Narrowing the Cone of Uncertainty Avoiding expensive late rework Ĥ Risk of Delaying Risk Management: Softwareġ0 20 50 100 2 Relative cost to fix defect 2 1 5 Requirements Design Code Development Acceptance Operation test test Smaller software projects Larger software projects Median (TRW survey) 80% 20% SAFEGUARD GTE IBM-SSD Phase in Which defect was fixed ĥ Steeper Cost-to-fix for High-Risk Elements
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