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A Winsor Brown and Ye Yang Center for Systems and Software Engineering

CS510 2007 “Tutorial” Presentation: Software Cost Estimation Tools – COCOMO II and COCOTS. A Winsor Brown and Ye Yang Center for Systems and Software Engineering University of Southern California {AWBrown, YangY}@sunset.usc.edu. Helpful Hints. What is COCOMO II.2000.3 vs. COCOMO II.2000

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A Winsor Brown and Ye Yang Center for Systems and Software Engineering

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  1. CS510 2007 “Tutorial” Presentation: Software Cost Estimation Tools – COCOMO II and COCOTS A Winsor Brown and Ye Yang Center for Systems and Software Engineering University of Southern California {AWBrown, YangY}@sunset.usc.edu CSCI 510 2007 COCOMO Tutorial

  2. Helpful Hints What is COCOMO II.2000.3 vs. COCOMO II.2000 • A third code variant of COCOMO II.2000 (in book’s CD) • Added more function point conversion tables • “fixed” the Adapted/Reused Code size input • … • Based on 2000 USC model calibration of COCOMOcombined Expert Judgement and Data using a Bayesian approach If you’ve installed COCOMO II.2000.3 correctly • On line Help is available • Scale factor value shows on 2nd open/change • Charts and COPSEMO are available CSCI 510 2007 COCOMO Tutorial

  3. I RR VCR LCO ACR IOC LCA PRR DCR OCR CCD RUP/ICM Anchor Points Enable Concurrent Engineering CSCI 510 2007 COCOMO Tutorial

  4. COCOMO Black Box Model product size estimate development, maintenance cost and schedule estimates product, process, platform, and personnel attributes COCOMO II cost, schedule distribution by phase and activity(for Elaboration and Construction!) reuse, maintenance, and increment parameters organizational project data local recalibration to organizational data CSCI 510 2007 COCOMO Tutorial

  5. COCOMO Sub-models • Applications Composition involves rapid development or prototyping efforts to resolve potential high-risk issues such as user interfaces, software/system interaction, performance, or technology maturity. It’s sized with application points (weighted screen elements, reports and 3GL modules). • The Early Design model involves exploration of alternative software/system architectures and concepts of operation using function points and a course-grained set of 7 cost drivers. • The Post-Architecture model involves the actual development and maintenance of a software product using source instructions and / or function points for sizing, with modifiers for reuse and software breakage; a set of 17 multiplicative cost drivers; and a set of 5 factors determining the project's scaling exponent. CSCI 510 2007 COCOMO Tutorial

  6. COCOMO Effort Formulation CSCI 510 2007 COCOMO Tutorial

  7. More helpful hints • Edit / Add Module Or Click on • Set Size: Click on • Select “SLOC” Method • Enter SLOC CSCI 510 2007 COCOMO Tutorial

  8. 1st Run of COCOMO II (cont.) CSCI 510 2007 COCOMO Tutorial

  9. Coverage of SDLC’s Processes • Original COCOMO was predicated on the waterfall process • single-pass, sequential progression of requirements, design, code, test • Still applicable (see Appendix A of SwCEwCII)! • Modern processes are concurrent, iterative, incremental, and cyclic • e.g. Rational Unified Process (RUP), the USC Model-Based Architecting and Software Engineering (MBASE) process • Effort and schedule are distributed among different phases and activities in MBASE/RUP/ICM per work breakdown structure of chosen process CSCI 510 2007 COCOMO Tutorial

  10. MBASE Phase Distributions • see COCOMO II book for complete phase/activity distributions Phase Effort % Schedule % Inception 6 12.5 Elaboration 24 37.5 Construction 76 62.5 Transition 12 12.5 COCOMO Total 100 100 Project Total 118 125 CSCI 510 2007 COCOMO Tutorial

  11. I RR VCR LCO ACR IOC LCA PRR DCR OCR CCD RUP/ICM Anchor Points Enable Concurrent Engineering CSCI 510 2007 COCOMO Tutorial

  12. COPSEMO Distributes Effort & Schedule CSCI 510 2007 COCOMO Tutorial

  13. More Helpful Hints – 3 Never do an estimate without REVL! CSCI 510 2007 COCOMO Tutorial

  14. 2nd Run COCOMO II • Set REVL to 15% (a good first guess) CSCI 510 2007 COCOMO Tutorial

  15. Cost Factors • Significant factors of development cost: • SIZE! (the most significant factor) • scale drivers are sources of exponential effort variation • cost drivers are sources of linear effort variation • product, platform, personnel and project attributes • effort multipliers associated with cost driver ratings • Defined to be as objective as possible • Each factor is rated between very low and very high per rating guidelines • relevant effort multipliers adjust the cost up or down CSCI 510 2007 COCOMO Tutorial

  16. Scale Drivers • Precedentedness (PREC) • Degree to which system is new and past experience applies • Development Flexibility (FLEX) • Need to conform with specified requirements • Architecture/Risk Resolution (RESL) • Degree of design thoroughness and risk elimination • Team Cohesion (TEAM) • Need to synchronize stakeholders and minimize conflict • Process Maturity (PMAT) • SEI CMM process maturity rating CSCI 510 2007 COCOMO Tutorial

  17. Scale Factors • Sum scale factors SFi across all of the factors to determine a scale exponent, B, using B = .91 + .01 SSFi CSCI 510 2007 COCOMO Tutorial

  18. Cost Drivers • Product Factors • Reliability (RELY) • Data (DATA) • Complexity (CPLX) • Reusability (RUSE) • Documentation (DOCU) • Platform Factors • Time constraint (TIME) • Storage constraint (STOR) • Platform volatility (PVOL) • Personnel factors • Analyst capability (ACAP) • Program capability (PCAP) • Applications experience (APEX) • Platform experience (PLEX) • Language and tool experience (LTEX) • Personnel continuity (PCON) • Project Factors • Software tools (TOOL) • Multisite development (SITE) • Required schedule (SCED) CSCI 510 2007 COCOMO Tutorial

  19. Example Cost Driver - Required Software Reliability (RELY) • Measures the extent to which the software must perform its intended function over a period of time. • Ask: what is the effect of a software failure? CSCI 510 2007 COCOMO Tutorial

  20. Many Organizations Provide Generic Guidance • PREC • RESL See Table 2.42 in SwCEwCII PMAT and DATA most commonly misunderstood CSCI 510 2007 COCOMO Tutorial

  21. Significant CSCI577A Effort Multipliers CSCI 510 2007 COCOMO Tutorial

  22. Reused and Modified Software • Effort for adapted software (reused or modified) is not the same as for new software. • Approach: convert adapted software into equivalent size of new software. CSCI 510 2007 COCOMO Tutorial

  23. Nonlinear Reuse Effects • The reuse cost function does not go through the origin due to a cost of about 5% for assessing, selecting, and assimilating the reusable component. • Small modifications generate disproportionately large costs primarily due the cost of understanding the software to be modified, and the relative cost of interface checking. CSCI 510 2007 COCOMO Tutorial

  24. COCOMO Reuse Model • A nonlinear estimation model to convert adapted (reused or modified) software into equivalent size of new software: CSCI 510 2007 COCOMO Tutorial

  25. COCOMO Reuse Model (cont’d) • ASLOC - Adapted Source Lines of Code • ESLOC - Equivalent Source Lines of Code • AAF - Adaptation Adjustment Factor • DM - Percent Design Modified. The percentage of the adapted software's design which is modified in order to adapt it to the new objectives and environment. • CM - Percent Code Modified. The percentage of the adapted software's code which is modified in order to adapt it to the new objectives and environment. • IM - Percent of Integration Required for Modified Software. The percentage of effort required to integrate the adapted software into an overall product and to test the resulting product as compared to the normal amount of integration and test effort for software of comparable size. • AA - Assessment and Assimilation effort needed to determine whether a fully-reused software module is appropriate to the application, and to integrate its description into the overall product description. See table. • SU - Software Understanding. Effort increment as a percentage. Only used when code is modified (zero when DM=0 and CM=0). See table. • UNFM - Unfamiliarity. The programmer's relative unfamiliarity with the software which is applied multiplicatively to the software understanding effort increment (0-1). CSCI 510 2007 COCOMO Tutorial

  26. 4th Run COCOMO II CSCI 510 2007 COCOMO Tutorial

  27. Sizing - Lines of Code • Source Lines of Code (SLOCs) = logical source statements • Logical source statements = data declarations + executable statements • Executable statements cause runtime actions • Declaration statements are non-executable statements that affect an assembler's or compiler's interpretation of other program elements • CodeCount tool available on CSSE website CSCI 510 2007 COCOMO Tutorial

  28. Size Estimation • By analogy with Wide-Band Delphi before LCO • Ask each team member what they think the size might be • Apply personal experience, • Look at completed projects, • Guess (WAG), • SWAG based on “modules” known to date • Collect and share in a meeting: discuss why/how different people made their estimate • Repeat • When stable, Size = (H + 4 X Ave. + L)/6 CSCI 510 2007 COCOMO Tutorial

  29. Part II: COCOTS Model and Demo CSCI 510 2007 COCOMO Tutorial

  30. Relationship between CII and COCOTS CSCI 510 2007 COCOMO Tutorial

  31. COCOTS • COCOTS is the acronym for the Constructive COTS integration cost estimation model • A member of the USC COCOMO II family of cost estimation models • For estimating the expected initial cost of integrating COTS software into a new software system development • Three sub-models: • COTS Assessment • COTS Tailoring • COTS Glue code development CSCI 510 2007 COCOMO Tutorial

  32. COTS Assessment Sub-model • COTS Assessment: the activity of determining the appropriateness or feasibility of using specific COTS products to fulfill required system functions. CSCI 510 2007 COCOMO Tutorial

  33. COTS Tailoring Sub-model • COTS Tailoring: the activity associated with setting or defining shell parameters or configuration options available for a COTS product, but which do not require modification of COTS source code, including defining I/O report formats, screens, etc. CSCI 510 2007 COCOMO Tutorial

  34. COTS Glue Code Sub-model • COTS “glue” code/integration refers to software developed in-house and composed of • 1) code needed to facilitate data or information exchange between the COTS and the system or other COTS; • 2) code needed to connect the COTS into the system or other COTS but does not necessarily enable data exchange; • 3) code needed to provide required functionality missing in the COTS AND which depends upon or must interact with the COTS. CSCI 510 2007 COCOMO Tutorial

  35. COTS Glue Code Sub-model Formula CSCI 510 2007 COCOMO Tutorial

  36. Total COCOTS Estimation • Sum of three sub-models’ estimates: • EffortCOT = EffortA + EffortT + EffortGC • “Grand” total effort for developing a COTS-Based System (CBS): • EffortCBS = EffortCOC + EffortCOT CSCI 510 2007 COCOMO Tutorial

  37. Questions and Answers • Questions from you? • Question from HHGG: “The great question of Life, The Universe and Everything”. • Answer: 42! (1010102) CSCI 510 2007 COCOMO Tutorial

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