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