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Pragmatic Software Cost Estimation

Pragmatic Software Cost Estimation. Mike Calvanese ISYS 420. Problems. Lack of well-documented case studies of projects that use iterative development approach Data that does exist from projects is suspect in terms of consistency and comparability

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Pragmatic Software Cost Estimation

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  1. Pragmatic Software Cost Estimation Mike Calvanese ISYS 420

  2. Problems • Lack of well-documented case studies of projects that use iterative development approach • Data that does exist from projects is suspect in terms of consistency and comparability *The software industry has inconsistently defined units of measure

  3. Debates Among Developers • Which cost estimation model to use • Whether to measure software size in source lines of code or function points • What constitutes a good estimate

  4. Measurements of Software Size • Source Lines of Code (SLOC) • Function Points • Ad Hoc/Subjective

  5. Source Lines of Code • Advantages *Most people in the industry are comfortable with its general ‘mass’ *SLOC tends to work well in ‘custom-built’ applications *SLOC measurement is easy to automate and instrument *SLOC are particularly useful in later stages of the project life-cycle

  6. Source Lines of Code • Disadvantages *SLOC can become ambiguous due to changes in programming and languages -Language advancements -Automatic source code generation -Object orientation *Different programmers have different styles

  7. Function Points • Advantages *Independent of Technology -Works well for those on the project who are not technology-oriented *Much better primitive unit for comparisons among projects and organizations *Works well for cross-project or cross-organization comparisons *Works well in early stages of the project life-cycle when actual coding is not yet in full production

  8. Function Points • Disadvantages * Primitive definitions are abstract * Measurements are not easily derived directly from the evolving artifacts

  9. Still Very Inexact Conventional cost models have been described as “within 20% of actuals, 70% of the time.” This is scary to investors and stakeholders, as very seldom are variations of estimates ‘for the better’.

  10. Attributes of a Good Software Cost Estimate • It is conceived and supported by the project manager, architecture team, development team, and test team accountable for performing the work. • It is accepted by all stakeholders as ambitious but realizable. • It is based on a well-defined software cost model with a credible basis. • It is based on a database of relevant project experience that includes similar processes, similar technologies, similar environments, similar quality requirements, and similar people. • It is defined in enough detail so that its key risk areas are understood and the probability of success is objectively assessed.

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