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The use of FPA is on the rise again, at least in Requests for Proposal for new contracts. But what is a function point and what can you do with it or should better not be done. I gave my colleagues a brief introduction, that appeared to be interesting to a much wider audience, so I translated the original Dutch presentation to English.
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FPA
Frank Vogelezang
FOR
2FPA for DummiesAgenda
What is FPA
How does FPA work
What can you do with FPA
What should better not be done with FPA
Who owns FPA
3FPA for Dummies What is FPA
FPA stands for FunctionPointAnalysis
What the software should be able to do (functionality)Functionexpressed in a number Pointbased on an objectively described method Analysis
Something intangible like functionality becomes a physical number that can be used for calculations
4FPA for Dummies How does function point analysis work
External Input
External Output
External Inquiry
External input files
Internal logical files
5FPA for Dummies How does function point analysis work
Counting function points Based on established criteria each element is
classified:
Each classification has its own scoresInternal files 7 10 15External interfaces 5 7 10External input 3 4 6External output 4 5 7External inquiry 3 4 6
A function point never travels alone
Simple
ComplexAverage
6FPA for Dummies 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
7FPA for Dummies 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
8FPA for Dummies What should better not be done with FPA
In estimating packaged software the relation with the size expressed in function points is unclear:
4993 Cool Convertible
4993 Truck
4993 Schaufelbagger
IWSM 2012 : Estimating Packaged Software Implementations - The first part of a framework
9FPA for Dummies 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
Computable : Goed aanbesteden op basis van functiepunten
ISBSG : The cost of speed
10FPA for Dummies What can you do with FPA – the really hard part
Hours / cost do not only depend on size, but on schedule time as well
Minimal time
Optimal effort
Realistic
Schedule time
Effor
t
11FPA for Dummies 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
COSMICbut 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
12FPA for Dummies Who owns the function point method
In the Netherlands the most commonly used method is the one from NESMA NESMA = Netherlands Software Metrics users AssociationThis method is cerrtified as ISO/IEC 24570
Worldwide the most commonly used FPA method is the one from IFPUGIFPUG = International Fuction Point User GroupThis method is cerrtified as ISO/IEC 20926
13
WatKostIT.blogspot.nl
ThePriceofIT.blogspot.com
@FrankVogelezang
FrankVogelezang
www.linkedin.com/in/frankvogelezang
