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Benevol 2011

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Alexander used these slides during for his presentation at BeNeVol 2011 in Brussels, Belgium. That is after he blew the fuses in the entire building. ...

Alexander used these slides during for his presentation at BeNeVol 2011 in Brussels, Belgium. That is after he blew the fuses in the entire building.

Paper:
Serebrenik A, Vasilescu B and van den Brand M (2011), "Similar tasks, different effort: Why the same amount of functionality requires different development effort?", In Proceedings of the 10th Belgian-Netherlands Software Evolution Seminar, pp. 4-5.

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  • B. Kitchenham, S. L. Pfleeger, B. McColl, and S. Eagan, “An empirical study of maintenance and development estimation accuracy,” Journal of Systems and Software, vol. 64, no. 1, pp. 57–77, 2002.
  • > lm2 summary(lm2)Call:lm(formula = log(SWE) ~ log(AFP))Residuals: Min 1Q Median 3Q Max -4.3960 -0.6584 0.0272 0.6760 3.3857 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 2.92717 0.09386 31.19 < 2.2e-16 df6$residuals <- lm2$residualsdiffEff_ineqMeasures_on_df(df6)

Benevol 2011 Benevol 2011 Presentation Transcript

  • Similar Tasks, Different Effort:Why the Same Amount ofFunctionality RequiresDifferent Development Effort? Alexander Serebrenik Bogdan Vasilescu Mark van den Brand
  • Why do some systems require more effort? • Empirical study • ISBSG version 11 • largest publically available collection: 5052 projects • 118 project attributes, including − amount of functionality − work effort • Not all projects are suited for the study • self-reporting different data quality • different ways of measuring project attributes/ W&I / MDSE 23-4-2012 PAGE 1
  • Project selection ISBSG v.11 5052 Effort Staff hours (recorded) 3537 Full development lifecycle 2261 Project-specific activities only 2079 Functionality IFPUG 1661 Data quality “A” or “B” 1609/ W&I / MDSE 23-4-2012 PAGE 2
  • Effort and Functionality Distributions • Effort: • Adjusted FP or unadjusted FP • skewed, outliers • Adjusted is more reliable [Kitchenham et al. JSS, 2002] • skewed, outliers/W&I / MDSE 23-4-2012 PAGE 3
  • More functionality more effort required • Log-transformation for the skewness / outliers problem • Adequate • p-value for the F- stat ≤ 2.2*10-16, • p-values intercept and coefficient ≤ log(SWE) = 2.2*10-16, 2.92717 + • residuals show a 0.84617 * log(AFP) chaotic pattern/ W&I / MDSE 23-4-2012 PAGE 4
  • Why do some systems require more effort? • Closer look at the residuals • technical aspects: − primary programming language, language type, development type, platform, and architecture • organization type • intended market • year of project • Problem of ISBSG • missing values due to self-reporting/ W&I / MDSE 23-4-2012 PAGE 5
  • What attributes impact the development effort? • Goal: compare different project attributes • ISBSG – 118 attributes • Remove projects with missing values • More attributes less projects • Keep projects with missing values • NA-category becomes too important • We choose • primary programming language, language type, organization type, intended market, year of project, development type, platform, architecture/ W&I / MDSE 23-4-2012 PAGE 6
  • Explanation of impact • Partition individuals in groups • Partition = explanation [Cowell, Jenkins 1995] • Inequality within the groups and between the groups − Inequality indices • Better explanation: more inequality between the groups − Lila is better than red − Partition refinement doesn’t deteriorate the explanation/ SET / W&I / TU/e PAGE 7
  • Which inequality index? • We need a decomposable index applicable to negative values/ W&I / MDSE 23-4-2012 PAGE 8
  • Results Indonesia:Project attribute Explanation % expenditure by educ.level 32.6% missing values No Missing values N = 151 N = 1609Primary Indonesia: 25,37% 16,11%programming expenditure by Linux: LOC bylanguage province 18.9% package 17.4%Organisation type 17,59% 18,36%Year of the project 10,88% 5,41%Architecture 8,68% Linux: LOC by 3,35%Development 5,43% impl lang 5.32% 5,05%PlatformIndonesia:Intended Market by expenditure 4,61% 1,57% Linux: LOC byLanguage type2.6% gender 2,45% maintainer 4.45% 1,28%Development Type/ W&I / MDSE 23-4-2012 PAGE 9 0,05% 0,07%
  • Conclusions • Three groups of attributes • High-impact: primary programming language, organization type • Middle-impact − year of the project [cf. Kitchenham et al. 2002] − architecture, development platform • Low impact: intended market, language type, devel’t type • A new technique for analysis of effort fp/ W&I / MDSE 23-4-2012 PAGE 10
  • Future work • Partition should be MECE • “Wholesale & Retail Trade” and “Financial, Property & Business Services” • New aggregation/explanation techniques • Conjecture: relative importance of attributes will be the same for other datasets • Models based on data from multiple companies are not applicable when one company data is considered [Ruhe 1999] • Both multi-company and company-specific studies are needed/ W&I / MDSE 23-4-2012 PAGE 11