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Requirements Elaboration

Requirements Elaboration. Ali Afzal Malik, Barry Boehm, USC-CSSE Annual Research Review March 18, 2008. Outline. Motivation Empirical study Methodology Results Findings Future work References. Motivation. Cost estimation - GIGO. Cost Model. Research Objectives. Early estimation

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Requirements Elaboration

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  1. Requirements Elaboration Ali Afzal Malik, Barry Boehm, USC-CSSE Annual Research Review March 18, 2008 ©USC-CSSE

  2. Outline • Motivation • Empirical study • Methodology • Results • Findings • Future work • References ©USC-CSSE

  3. Motivation • Cost estimation - GIGO Cost Model ©USC-CSSE

  4. Research Objectives • Early estimation • Use goals • Phenomenon of Requirements Elaboration • High-level Goals  Low-level Requirements • Characterize cause of variation in elaboration ratios ©USC-CSSE

  5. Requirements Elaboration Levels Use Case Level of Detail Scale(Cockburn, 2001) ©USC-CSSE

  6. Research Approach • Related previous work • Agent-based approach (Letier and van Lamsweerde, 2002) • GBRAM (Antón, 1996) • How is our work different? • Focus on the process itself • Obtain detailed project data • Analyze causes of variation ©USC-CSSE

  7. Empirical Study* • SE I (Fall) and SE II (Spring) • 2004 – 2006 • 20 real-client, MS-student, team projects • Process: MBASE/RUP • Project selection • Custom development • Complete documentation *A. Malik, B. Boehm, “An Empirical Study of Requirements Elaboration”, Submitted in 16th IEEE International Requirements Engineering Conference. ©USC-CSSE

  8. Empirical Study (2) ©USC-CSSE

  9. Project Process ©USC-CSSE

  10. Methodology • Relationship between capability goals and capability requirements • Documents and milestones considered • LCO-OCD*: Capability goals at the end of the Inception phase • IOC-SSRD#: Capability requirements at the end of the Construction phase • 7 metrics • 4 direct • 3 derived * Life Cycle Objectives – Operational Concept Description # Initial Operational Capability – System and Software Requirements Definition ©USC-CSSE

  11. Metrics ©USC-CSSE

  12. Derived Metrics • NCGA = NCGI – NCGR • NCRA = NCRD – NCRN • EF = NCRA / NCGA ©USC-CSSE

  13. Results ©USC-CSSE

  14. Results (2) (2): 2 data points ©USC-CSSE

  15. Findings • WUA: Well-understood applications • ICA: Intermediate clarity applications • VUA: Vaguely understood applications ©USC-CSSE

  16. Outliers WUA ICA VUA EF 0 1 1.5 2 EF ranges defining groups Findings (2) • Project groups based on EF ranges • WUA: Well-understood applications • ICA: Intermediate clarity applications • VUA: Vaguely-understood applications ©USC-CSSE

  17. Findings (3) • No one-size-fits-all formula for requirements elaboration • Knowledge of a project’s type gives a hint about its EF value e.g. all projects in the VUA group are of type “Web-based Database” • Benefits of early determination of a project’s group • better estimates • save time and effort ©USC-CSSE

  18. Future Work • Relationship between LOS goals and LOS requirements • Relationship between current metrics and those provided by architectural documents • Relationship between current metrics and software size metrics • Analysis of industrial data ©USC-CSSE

  19. References • Books • Cockburn, A., Writing Effective Use Cases, Addison-Wesley, 2001. • Kruchten, P., The Rational Unified Process: An Introduction, Addison-Wesley, 2003. • Conference papers • A. I. Antón, “Goal-based requirements analysis”, Proc. of the IEEE Int. Req. Eng. Conf. (RE), 1996, pp. 136–144. • B. Boehm, “Anchoring the Software Process”, IEEE Software 13(4), 1996, pp. 73-82. • E. Letier and A. van Lamsweerde. “Agent-based tactics for goal-oriented requirements elaboration”, Proc. of the IEEE Int. Conf. on Soft. Eng. (ICSE), 2002, pp. 83–93. • Miscellaneous • Boehm, B., Klappholz, D., Colbert, E., et al., “Guidelines for Lean Model-Based (System) Architecting and Software Engineering (LeanMBASE)”, Center for Software Engineering, University of Southern California, 2005. • http://sunset.usc.edu/csse/courseroot/course_list.html#577a • http://sunset.usc.edu/csse/courseroot/course_list.html#577b ©USC-CSSE

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