Home Practices 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.

Rating:  / 107
June 02, 2004

SEARCH DEV SHED

TOOLS YOU CAN USE

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.

 Component Type Component Complexity Low Average High Total External Inputs __* 3=EI1 __* 4=EI2 __* 6=EI3 EI1+EI2+EI3 External Outputs __* 4=EO1 __* 5=EO2 __* 7=EO3 EO1+EO2+EO3 External Inquiries __* 3=EQ1 __* 4=EQ2 __* 6=EQ3 EQ1+EQ2+EQ3 Internal Logical Files __* 7=ILF1 __* 10=ILF2 __* 15=ILF3 ILF1+ILF2+ILF3 External Interface Files __* 5=EIF1 __* 7=EIF2 __* 10=EIF3 EIF1+EIF2+EIF3 Total UAF (EI1+EI2+EI3) + (EO1+EO2+EO3) + (EQ1+EQ2+EQ3) + (ILF1+ILF2+ILF3) + (EIF1+EIF2+EIF3)

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:

1. Data communication
2. Distributed functions
3. Performance objectives
4. Heavily used configuration
5. Transaction rate
6. Online data entry
7. End-user efficiency
8. Online update
9. Complex processing
10. Reusability
11. Installation ease
12. Operational ease
13. Multiple sites
14. 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