HomePractices Page 4 - An Overview of Function Point Analysis
Unadjusted Function Points - Practices
Function Point Analysis is a structured technique of classifying components of a system. It is a method used to break systems down into smaller components so that they can be better understood and analyzed. Function Point Analysis provides a structured technique for problem solving.
Each function point count is multiplied by the numerical rating derived from the above table(s) to determine the complexity rated value. The complexity rated values on each row are summed across the table. This gives the total value for each type of component. The totals for all the components are then summed up to arrive at the total number of Unadjusted Function Points or UAF.
The Value Adjustment Factor (VAF) is based on fourteen General System Characteristics (GSC's). The degrees of influence range on a scale of zero to five, from no influence to strong influence. The GSCs are listed below:
Data communication
Distributed functions
Performance objectives
Heavily used configuration
Transaction rate
Online data entry
End-user efficiency
Online update
Complex processing
Reusability
Installation ease
Operational ease
Multiple sites
Facilitate change
VAF = 0.65 + (Sum of degrees of Influence of the fourteen GSCs)/100
The final Function Point Count is obtained by multiplying VAF by the Unadjusted Function Point (UAF).
FP = UAF * VAF
Summary:
Function points, as discussed earlier, can be used to size software applications accurately, as sizing is an important factor in determining productivity. Since function point has a unique and consistent method, different people measuring them will give almost the same result with very little margin of error. A non-technical person can easily understand function points, which helps in communicating the same to the end-user effectively and easily.
Glossary of Terms:
DET Data Element Type EIF External Interface File EI External Inputs EO External Outputs EQ External Inquiries FTR File Types Referenced GSC General System Characteristics ILF Internal Logical Files UAF Unadjusted Function Point VAF Value Adjustment Factor
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