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“Why Size Matters”

NYCity SPIN Presentiation New York NY, May 2003. “Why Size Matters”. Michael C. Mah Managing Partner QSM Associates, Inc. 75 South Church Street Pittsfield, MA 01201 413-499-0988 Fax 413-447-7322 e-mail: michael.mah@qsma.com. Web Site: www.qsma.com. Ed Yourdon on “Sizing”.

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“Why Size Matters”

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  1. NYCity SPIN Presentiation New York NY, May 2003 “Why Size Matters” Michael C. MahManaging PartnerQSM Associates, Inc.75 South Church StreetPittsfield, MA 01201413-499-0988Fax 413-447-7322e-mail: michael.mah@qsma.com Web Site: www.qsma.com

  2. Ed Yourdon on “Sizing”.. “If you underestimate the size of your next project, common sense says that it doesn’t matter which methodology you use, what tools you buy, or even what programmers you assign to the job.”

  3. Rifkin’s* Criteria:Estimation Processes • Commitments have to be based on work [scope] to be performed; therefore, there must be agreement on this • Estimates have to be based on a) the work to be performed and b) historical records of performance • Commitments must not exceed the capability to perform, or else there is no reason to estimate * Stan Rifkin, Master Systems Inc. (formerly with Carnegie Mellon SEI)

  4. Sizing Has a Purpose • Productivity Measurement (Historical View) • Project Estimation (Future View) • Project Risk Tracking (Present View)

  5. Make Commitment Support FutureCommitments ManageCommitment Commitment “In-Flight”Tracking Analyze Performance on Commitment Software Measurement and Management – 3 Key Areas Assess Viable Strategies ProjectEstimation ProjectHistory Post Project Analysis Monitor Status & Replan

  6. QSM Productivity Index (PI)(industry values by application type) Information Business Scientific System Engineering Process Control Telecommunications Command and Control Real Time Real Time Avionics Microcode 0 2 4 6 8 10 12 14 16 18 20 22 24 Productivity Index (PI) w/ ±1 Standard Deviation

  7. Example – Historical and New Project Assessment

  8. Early Warning - Tracking Size for “In-Flight” Projects Data are Consistentlyin the Amber Region Example

  9. Cutter Consortium Study on Software Estimation Source: Cutter Consortium, Benchmark Review Vol. 2, No. 8

  10. Perceptions of Size Microsoft Brutal Monopolist? Microsoft Industry Leader? Function Points areEvil Function Points are a Savior Counting Code is Relevant Counting Code is Stupid Different views aren’t necessarily crazy None of us has sole possession of the truth Not always Right/Wrong, more often a case of Right/Right

  11. Ed Yourdon on “Sizing”.. “Studies by the Carnegie Mellon SEI indicate that the most common failing ofLevel 1 (Ad-hoc) software organizations is an inability to make size estimates accurately.”

  12. The Common Obstacle to Software Sizing “Never been asked to consider size up front or after the fact; always equated size to effort i.e. number of hours”

  13. Software Sizing How do we Describethe Volume of Software?

  14. Many Functional Metrics Can be Used to Represent S/W Size • Subsystems • Entities • Function points • Modules • Objects • Programs • SLOC • Actions/Instructions/Statements

  15. Functional Metrics(Proxies) • They all represent what has to be created, but at different levels of abstraction • They all can be useful • Knowing the scaling relationships, enables us to use them effectively

  16. Size – Scaling Relationships Typical Examples • Objects 150 – 250 loc/Object • Function Points 30 - 400 • Modules 100 - 500 • Programs 200 - 1400 • Subsystems 4,000 - 12,000 Can Be Determined from Data

  17. For Additional Information Contact: Michael Mah Managing Partner QSM Associates Inc. Clocktower Building 75 So. Church St., Suite 600 Pittsfield, MA 01201 Email: michael.mah@qsma.com Web url: www.qsma.com

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