The Business Case for Requirements Engineering RE’2003 12 September 2003 Donald Firesmith Acquisition Improvement Team Acquisition Support Program Software Engineering Institute (SEI) Carnegie Mellon University Pittsburgh, PA 15213 © 2003 by Carnegie Mellon University

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In a Nut Shell • Requirements first opportunity to screw up • Many requirements engineers aren’t • Requirements typically contain many defects • Requirements impact all down-stream work • Cost to fix defects increases rapidly the earlier they are introduced • Requirements primary reason for failure

© 2003 by Carnegie Mellon University

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First Opportunity to Fail There are many chances to fail on any project: • Contracting • Requirements Engineering • Architecting • Design • Implementation • Integration • Testing • Etc. Requirements first engineering chance to fail. © 2003 by Carnegie Mellon University

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Many Requirements Engineers Aren’t Requirement Myth: • Since most requirements are specified in narrative English and most employees are minimally literate, managers often think that anyone (including low-level new hires) can do requirements engineering. Requirements engineers lack training in: • Requirements Tasks: • Requirements Identification • Requirements Analysis • Requirements Specification • Requirements Management • Requirements Techniques (e.g., use case modeling) • Requirements Tools © 2003 by Carnegie Mellon University

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Requirements Contain Defects The percentage of defects originating during requirements engineering are estimated as: • 50% (Karl Wiegers, 2001) • 42% (A Wingrove) • 60-64% (requirements and design – EBG Consulting) Requirements typically lack: • Cohesiveness, Completeness, Correctness, Consistency, Currency, Essential, Feasibility, Lack of Ambiguity, Relevance, Testability, Usability, Validatability

© 2003 by Carnegie Mellon University

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Requirements Engineering Impacts Requirements Engineering impacts: • Management (scope management) • Architecture (architecturally-significant requirements) • Design and Implementation • Testing • Quality Engineering (determines defects) • Safety Engineering (safety requirements) • Security Engineering (security requirements) • Reuse • Training Requirements Defects Snowball © 2003 by Carnegie Mellon University

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Defect Costs Are Excessive Requirements engineering defects cost: • 50-200 times as much to correct once fielded. (Barry Boehm, 1988) • 10-100 times as much to correct once fielded (Steve McConnell, 2001) • 15 times as much to correct once fielded (IBM System Sciences Institute – all defects so requirements worse) • 10 times as much to correct during testing (Hughes Aircraft) Reworking requirements defects on most software development projects cost: • 40-50% of the effort (Capers Jones) • 80% of the effort (Karl Wiegers, 2001) © 2003 by Carnegie Mellon University

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Bad Requirements Cause Failures Requirements problems are the single number one cause of project failure: • Significantly over budget • Significantly past schedule • Significantly reduced scope • Poor quality applications • Not significantly used once delivered • Cancelled © 2003 by Carnegie Mellon University

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Conclusion Requirements Engineering: • Starts project on the right foot • Turns requirements workers into trained requirements engineers • Eliminates and minimizes defects • Improves architecting, design, implementation, testing, QA, security, safety, etc. • Decreases development and lifecycle costs • Increases probability of success © 2003 by Carnegie Mellon University

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Contact Information Donald Firesmith Senior Member of the Technical Staff Acquisition Improvement Team Acquisition Support Program Telephone: 412-268-6874 Email: [email protected] U.S. Mail: Software Engineering Institute (SEI) Carnegie Mellon University Pittsburgh, PA 15213-3890 World Wide Web: http://www.sei.cmu.edu/ http://www.donald-firesmith.com/ © 2003 by Carnegie Mellon University

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The Business Case for Requirements Engineering - Software ...

Sep 12, 2003 - The Business Case for. Requirements Engineering ... Implementation. • Integration. • Testing ... (e.g., use case modeling). • Requirements Tools ...

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