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Nelly Condori-Fernandez, Luigi Buglione, Maya Daneva, Olga Ormandjieva                              SERA 2010 - Condori-Fe...
Goals of the presentation:             presentation G1. Discuss the estimation process in a software project, movingfrom ...
Agendax   Software Requirements     FR vs NFR     NFR: Non-Functional Requirementsx   Sizing & Estimating     Why the n...
Software Requirements                 FR vs NFR• Q: what is a requirement? A: “A software capability that must be met or p...
Software Requirements                   NFR: Non-Functional Requirement• In literature, NFRs are referred to as…     -ili...
Agendax   Software Requirements     FR vs NFR     NFR: Non-Functional Requirementsx   Sizing & Estimating     Why the n...
Sizing & Estimating                   Why the need for sizing FRs and NFRs?• Effort is a function of Size• Most effort est...
Sizing & Estimating     Entities to be measured: STAR taxonomy                                         Organization/ SBU  ...
Sizing & Estimating              History of Functional Size Measurement Methods (FSMM)                                    ...
Sizing & Estimating                         COSMIC Measurement Method                                       « Front       ...
Sizing & Estimating                   Some thoughts on measurable entities…                                               ...
Sizing & Estimating                     Some thoughts on measurable entities…is something missing?•   Rationale: is the pr...
Sizing & Estimating                       Project Size Unit (PSU)•       Project Size Unit (PSU)         Origin: created ...
Sizing & Estimating                 Project Size Unit (PSU): an example1. Define HLR and refinethem into RHLR        UR2. ...
Sizing & Estimating                  Project Size Unit (PSU): an example4. Count tasks frequencies by type, SLC phase and ...
Sizing & EstimatingSizing measures and possible gathering moments in the SLC               SERA 2010 - Condori-Fernandez, ...
Agendax   Software Requirements     FR vs NFR     NFR: Non-Functional Requirementsx   Sizing & Estimating     Why the n...
A possible approach                       Predicting CFP with PSU    •   Early Size (in CFP) prediction of FR and NFR dete...
A possible approach                           Scale type and admissible transformationsScale type               Admissible...
A possible approach                 Analysis of scale types of PSU and CFP•    PSU: at least interval scale type     resp...
A possible approach                Refined relationships between CFP and PSU• Relationships between PSU and CFP PSU f = k1...
Agendax   Software Requirements     FR vs NFR     NFR: Non-Functional Requirementsx   Sizing & Estimating     Why the n...
First Results                   Experimental design: Research Questions and Variables1. Null hypothesis, H10. Project Func...
First Results                 Experimental Procedure 55 third-year students enrolled at Concordia  University (Montreal,  ...
First Results                           Context and sample projects•        Measurement Process:         Moving by the sa...
First resultsStudents’ Project Historical Data                 SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva...
First results                   Students’ Project Historical Data & Regression analysisHypothesis H10 is not rejected:Null...
First results                  Students’ Project Historical Data & Regression analysisHypothesis H20 is rejected:Medium si...
Agendax   Software Requirements     FR vs NFR     NFR: Non-Functional Requirementsx   Sizing & Estimating     Why the n...
Conclusions & Prospects•   Main Issue/Goal observed        Improve predicatibility of project effort estimation as earlie...
Thanks for your attention !          SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010   31
Nelly Condori-Fernandez <nelly@pros.upv.es>Luigi Buglione: <luigi.buglione@eng.it>Maya Daneva: <m.daneva@utwente.nl>Olga O...
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Experimental Study Using Functional Size Measurement in Building Estimation Models for Software Project Size

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The presentation proposes a possible hybrid approach for improving the estimation process, mixing two different viewpoint on software, looking both at the project as well as the product entities

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Transcript of "Experimental Study Using Functional Size Measurement in Building Estimation Models for Software Project Size"

  1. 1. Nelly Condori-Fernandez, Luigi Buglione, Maya Daneva, Olga Ormandjieva SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 1
  2. 2. Goals of the presentation: presentation G1. Discuss the estimation process in a software project, movingfrom initial requirements and their inner nature G2. Propose a possible hybrid approach for improving suchprocess, mixing two different viewpoints on software, looking bothat the project as well as the product entities G3. Measure in a controlled case study the effectiveness of suchapproach, noting possible issues for next improvements SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 2
  3. 3. Agendax Software Requirements  FR vs NFR  NFR: Non-Functional Requirementsx Sizing & Estimating  Why the need for sizing requirements?  The cone of uncertainty  Possible approaches  Project management approach  Project Size Unit (PSU)  Product functional approach  FSMM  COSMIC (ISO/IEC 19761)x A possible approach  Predicting CFP with PSU  Scale types  Refined relationships between CFP and PSUx Results  Context and sample projects  Student’s Project Historical Datax Conclusions & Prospects SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 3
  4. 4. Software Requirements FR vs NFR• Q: what is a requirement? A: “A software capability that must be met or possessed by a systemor system component to satisfy a contract, standard, specification, orother formally imposed documentation” [Leffingwell & Widrig, 2003]• General types of requirements:• Functional Requirements (FR) • Non- Functional Reqs (NFR)  ...For each shot the system  ..The response time shall be shall notify the players whether no more than 1 seconds for 95% the shot was a hit or miss... of responses and no more than 2 seconds for the remaining responses... SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 4
  5. 5. Software Requirements NFR: Non-Functional Requirement• In literature, NFRs are referred to as…  -ilities  Constraints  Quality attributes  Quality of service requirement  More?• IEEE-STD 830-1998 defines NFR as…  …“software requirement that describes not what the software will do, but how the software will do it…”  More definitions?• Nature of NFRs…  Subjective: viewed and interpreted differently by different people  Relative: interpretation and importance vary depending on the considered system  Interacting: attempts to achieve one NFR can hurt or help achievement of other  Global and scattered: one NFR affects multiple functionalities, or the whole system  More? SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 5
  6. 6. Agendax Software Requirements  FR vs NFR  NFR: Non-Functional Requirementsx Sizing & Estimating  Why the need for sizing requirements?  The cone of uncertainty  Possible approaches  Project management approach  Project Size Unit (PSU)  Product functional approach  FSMM  COSMIC (ISO/IEC 19761)x A possible approach  Predicting CFP with PSU  Scale types  Refined relationships between CFP and PSUx Results  Context and sample projects  Student’s Project Historical Datax Conclusions & Prospects SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 6
  7. 7. Sizing & Estimating Why the need for sizing FRs and NFRs?• Effort is a function of Size• Most effort estimation models use size as input for cost estimation  Most widely used metric of the size of a finished system is source lines of code (SLOC), delivered source instructions (DSI)  Two metrics of size applicable from the requirements specification phase are COSMIC Function Points (CFP) and Project Size Unit (PSU) • The cone of uncertainty Source: Boehm B., Software Engineering Economics, Prentice-Hall, 1981 SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 7
  8. 8. Sizing & Estimating Entities to be measured: STAR taxonomy Organization/ SBU ProjectResources Process Product fsu (e.g. UFP, CFP, …) Measurement SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 8
  9. 9. Sizing & Estimating History of Functional Size Measurement Methods (FSMM) MkII FPA 1.3 COSMIC-FFP – MkII ISO/IEC 19761 FPA NESMA IFPUG IFPUG 4.1Allan 4.0AlbrechtFPA 1980 1985 1990 1995 2000 Note: recently also FISMA FPA become an ISO International Standard (IS 29881:2008) SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 9
  10. 10. Sizing & Estimating COSMIC Measurement Method « Front « Back end » BOUNDARY end » USERS SOFTWARE ENTRIES STORE PERSISTENT DATA EXITS (‘WRITE’) Hardware DATA MANIPULATION Storage OR TRANSFORMATION or ENTRIESEngineered RETRIEVE PERSISTENT DATA Devices EXITS (‘READ’) SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 10
  11. 11. Sizing & Estimating Some thoughts on measurable entities… Container …an application (software) is not the project, (Project)therefore it cannot be represented in size terms onlyby a product metric such as FP (generically, as fsu). …the container (the project) is larger than itscontent (the product).…therefore, how could it be possible to size thebigger entity by the littler one and therefore to makeall the subsequent technical and economical Contentassumptions on such size unit? (Product)…a possible answer could be to consider at the same time (or at least, indifferent moments during the SLC lifetime) sizing measures for different entities(project, product) SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 11
  12. 12. Sizing & Estimating Some thoughts on measurable entities…is something missing?• Rationale: is the productivity ratio (as now applied) meaningful or not?  Overall productivity is underestimated (no “Quality | Technical points”) on the upper part of the formula to counterbalance the overall project effort on the lower part Project Size: the size of a software project, derived by quantifying the(implicit/explicit) user requirements refereable to the scope of the project itself SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 12
  13. 13. Sizing & Estimating Project Size Unit (PSU)• Project Size Unit (PSU)  Origin: created in 2003, it’s a PM-based technique for taking care of all possible user requirements – no matter the type – within the project framework  Goal: to create a virtual sizing unit for the whole project  Logical entity to count: WBS tasks, classified by several criteria  Weights: complexity weights by effort ranges (periodically revised)  Typical usage: internal (process improvement), but also external when the weighting system is stable among stakeholders (benchmarking)  Input: the IFPUG UFP formula  URL: www.semq.eu/leng/sizestpsu.htm PSU = ∑ ∑ taski * weight j i = M ,Q ,T j = H ,M , L • Application Scope  Projects, not only those for software ones (NewDev, Enh)  Project: “a temporary endeavor undertaken to create a unique product, service, or result” (PMBOK2008, Glossary) SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 13
  14. 14. Sizing & Estimating Project Size Unit (PSU): an example1. Define HLR and refinethem into RHLR UR2. Translate RHLRs intoWBS’s tasks, assigning aneffort 3. Classifying tasks per type (M/Q/T), SLC phase and complexity SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 14
  15. 15. Sizing & Estimating Project Size Unit (PSU): an example4. Count tasks frequencies by type, SLC phase and complexity5. Count PSU6. Compute effort distribution by task type (M/Q/T) and SLC phase SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 15
  16. 16. Sizing & EstimatingSizing measures and possible gathering moments in the SLC SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 16
  17. 17. Agendax Software Requirements  FR vs NFR  NFR: Non-Functional Requirementsx Sizing & Estimating  Why the need for sizing requirements?  The cone of uncertainty  Possible approaches  Project management approach  Project Size Unit (PSU)  Product functional approach  FSMM  COSMIC (ISO/IEC 19761)x A possible approach  Predicting CFP with PSU  Scale types  Refined relationships between CFP and PSUx Results  Context and sample projects  Student’s Project Historical Datax Conclusions & Prospects SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 17
  18. 18. A possible approach Predicting CFP with PSU • Early Size (in CFP) prediction of FR and NFR determines the likely future values of product size based on existing PSU measure of the same product • Advantages 1. allow for accurate size prediction of all FR and NFR, including those which are not (yet) stated in measurable terms 2. reduces the size measurement effort at this early stage• Theoretical aspect 1. Analyze the scale types of PSU and CFP 2. Given the lowest scale type, identify the corresponding to it type of admissible transformation (relation) between both units of measurement• Empirical aspect 1. Use available project data on PSU, CFP and Effort 2. Derive the prediction formula SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 18
  19. 19. A possible approach Scale type and admissible transformationsScale type Admissible transformations ExamplesNominal 1:1 mapping from M to M’ Labeling, classifying entitiesOrdinal Monotonic increasing function Preference, hardness, air quality, intelligence test (raw scores) from M to M’, that is, M(x) ≥ M(y) implies M’(x) ≥ M’(y)Interval M’=aM + b(a>0) Relative time, temperature (Fahreneit, Celsius), intelligence tests (standardized scores)Ratio M’=aM (a>0) Time interval, lenght, temperature (Kelvin)Absolute M’=M Counting entities Source: Fenton N. & Pfleeger S.L., Software Metrics: A Rigorous and Practical Approach, 2° ed., Course Tech., 1998, ISBN978-0534954253 SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 19
  20. 20. A possible approach Analysis of scale types of PSU and CFP• PSU: at least interval scale type  respects the additive property• CFP: at least ratio scale  Ratio of two values is meaningful• Both are valid size measurement units   theoretically there should exist an admissible transformation of type PSU = k * CFP + b(k > 0) SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 20
  21. 21. A possible approach Refined relationships between CFP and PSU• Relationships between PSU and CFP PSU f = k1* CFPf + b1 PSU n f = k 2 * CFPnf + b 2• PSU and CFP respect the additive property PSU = PSUf + PSU nf CFP = CFPf + CFPnf SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 21
  22. 22. Agendax Software Requirements  FR vs NFR  NFR: Non-Functional Requirementsx Sizing & Estimating  Why the need for sizing requirements?  The cone of uncertainty  Possible approaches  Project management approach  Project Size Unit (PSU)  Product functional approach  FSMM  COSMIC (ISO/IEC 19761)x A possible approach  Predicting CFP with PSU  Scale types  Refined relationships between CFP and PSUx Results  Context and sample projects  Student’s Project Historical Datax Conclusions & Prospects SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 22
  23. 23. First Results Experimental design: Research Questions and Variables1. Null hypothesis, H10. Project Functional Size determine estimated fromRQ1: In what extent does the product non-functional sizecannot be the project size? Product Functional Size.2. Null hypothesis, H20. product functional size Size cannot be estimatedRQ2: In what extent does the Project Non-Functional determine the project size? from Product Non-Functional Size. Type of Variables Response variable Product size (calculated by the students) (Dependent) Project size (calculated by an expert) Factor (Independent) Project size measurement method: PSU Product size measurement method: COSMIC and COSMIC-NFSM Parameters - Application domain (web-application domain), - Experience using size measurement methods, - Quality of requirements specification. SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 23
  24. 24. First Results Experimental Procedure 55 third-year students enrolled at Concordia University (Montreal, Group2 Group 3 Group 11 Group 1 Canada). Documentation MeasurementThe experiment was Applying CFP and NFSMorganised as mandatorypart of the “Software Requirement,Measurement” course Design and Analysis Applying PSU Work-Breakdown Structure Expert SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 24
  25. 25. First Results Context and sample projects• Measurement Process:  Moving by the same problem statement, each team had to: 1. estimate the effort in man/hours on the info available at the feasibility stage 2. calculate the two sizes (CFP, PSU) 3. realizing the web project 4. determine the actual effort at the project closure stage 5. calculate the two final sizes (CFP, PSU) • Size Units adopted:  COSMIC Measurement Manual, v3.0  Layers: Application layer  Perspective used: end user  PSU Measurement Manual, v1.21  4 complexity effort ranges based on projects’ data  H/MH/ML/L SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 25
  26. 26. First resultsStudents’ Project Historical Data SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 26
  27. 27. First results Students’ Project Historical Data & Regression analysisHypothesis H10 is not rejected:Null significance, p= 0.24However, excluding twodata points from theanalysis: PSU FUR = 1.003 * CFP − 29.897 FUR SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 27
  28. 28. First results Students’ Project Historical Data & Regression analysisHypothesis H20 is rejected:Medium significance, p= 0.033 PSU NFR = 4.61* CFPNFR + 29.04 SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 28
  29. 29. Agendax Software Requirements  FR vs NFR  NFR: Non-Functional Requirementsx Sizing & Estimating  Why the need for sizing requirements?  The cone of uncertainty  Possible approaches  Project management approach  Project Size Unit (PSU)  Product functional approach  FSMM  COSMIC (ISO/IEC 19761)x A possible approach  Predicting CFP with PSU  Scale types  Refined relationships between CFP and PSUx Results  Context and sample projects  Student’s Project Historical Datax Conclusions & Prospects SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 29
  30. 30. Conclusions & Prospects• Main Issue/Goal observed  Improve predicatibility of project effort estimation as earlier as possible by obtaining the lowest ARE/MREas possible• State-of-the-art  Typical usage of single sizing & estimation methods (e.g. expert-based, analogy, parametric-based), covering a single perspective per time• Possible solution  Use at least two sizing methods according to their pros&cons during the whole SLC phases• Challenge…  Predicting CFP of FUR and (more importantly) NFR moving from project scope knowledge captured in PSU estimates• Possible advantages  Early productivity analysis from the predicted CFP size  Such solution can be automated within a PM tool (e.g. MS-Project)• Next actions/Prospects  A wider application of such approach on a larger number of projects, in order to validate it and stress eventual weakenesses SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 30
  31. 31. Thanks for your attention ! SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 31
  32. 32. Nelly Condori-Fernandez <nelly@pros.upv.es>Luigi Buglione: <luigi.buglione@eng.it>Maya Daneva: <m.daneva@utwente.nl>Olga Ormandjieva: <ormanj@cse.concordia.ca> SERA 2010 - Condori-Fernandez, Buglione, Daneva, Ormanjieva © 2010 32
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