FPA for Dummies
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Function Point Analysis (FPA) quantifies software functionality into measurable points for evaluation and cost estimation. FPA involves classifying functions and calculating based on established criteria, but should avoid unrelated activities like design and licensing in its assessments. The commonly used FPA methods come from NESMA in the Netherlands and IFPUG globally, both certified by relevant ISO standards.
FPA for Dummies
- 2. FPA for Dummies 2 Agenda What is FPA How does FPA work What can you do with FPA What should better not be done with FPA Who owns FPA
- 3. FPA for Dummies 3 What is FPA FPA stands for Function Point Analysis What the software should be able to do (functionality) Function expressed in a number Point based on an objectively described method Analysis Something intangible like functionality becomes a physical number that can be used for calculations
- 4. FPA for Dummies 4 How does function point analysis work External Inquiry External Input External Output Internal logical files External input files
- 5. FPA for Dummies 5 How does function point analysis work Counting function points Based on established criteria each element is classified: Simple Complex Each classification has its own scores Internal files 7 10 15 External interfaces 5 7 10 External input 3 4 6 External output 4 5 7 External inquiry 3 4 6 A function point never travels alone
- 6. FPA for Dummies 6 What can you do with FPA Translate functionality into a physical number that can be used to calculate: Required amount of hours / cost Schedule time Basis for a fixed price (per unit) that is still variable The calculation depends on the technology used (Java, eBS, . . .) But it is not a linear calculation! Twice the size in function points is not twice as much hours / cost / time
- 7. FPA for Dummies 7 What should better not be done with FPA Take into account activities that have no direct relation to the amount of functionality of the software, like: Design / Specification Develop- and Testenvironments Data conversion Licences Combine all technologies in a single rate per function point Treat big and small projects the same in a single rate per function point Don’t take schedule compression into account in the rate per function point
- 8. FPA for Dummies 8 What should better not be done with FPA In estimating packaged software the relation with the size expressed in function points is unclear: 4993 Truck 4993 Cool Convertible 4993 Schaufelbagger IWSM 2012 : Estimating Packaged Software Implementations - The first part of a framework
- 9. FPA for Dummies 9 What can you do with FPA – the hard part Hours / cost per function point depend on the number of function points Hours / Cost Function points ISBSG : The cost of speed Computable : Goed aanbesteden op basis van functiepunten
- 10. FPA for Dummies 10 What can you do with FPA – the really hard part Hours / cost do not only depend on size, but on schedule time as well Effort Minimal time Realistic Optimal effort Schedule time
- 11. FPA for Dummies 11 Variations on the function point analysis theme NESMA has issued several guides: FPA for software enhancement (also in Portuguese) FPA applied to Data Warehousing Functional Sizing in a SOA environment (Dutch only) FPA in early phases They are not part of the ISO/IEC 24570 standard COSMIC but that is a whole different story / standard The additional guides can be downloaded free of charge from : www.nesma.nl Information on the COSMIC method is available on : www.cosmicon.com
- 12. FPA for Dummies 12 Who owns the function point method In the Netherlands the most commonly used method is the one from NESMA NESMA = Netherlands Software Metrics users Association This method is cerrtified as ISO/IEC 24570 Worldwide the most commonly used FPA method is the one from IFPUG IFPUG = International Fuction Point User Group This method is cerrtified as ISO/IEC 20926
- 13. WatKostIT.blogspot.nl ThePriceofIT.blogspot.com @FrankVogelezang FrankVogelezang frank.vogelezang@ordina.nl www.linkedin.com/in/frankvogelezang 13