Function point analysis

Function Point Analysis (FPA) is an ISO recognized method to measure the functional size of an information system. The functional size reflects the amount of functionality that is relevant to and recognized by the user in the business. It is independent of the technology used to implement the system.

The unit of measurement is "function points". So, FPA expresses the functional size of an information system in a number of function points (for example: the size of a system is 314 FPs).

The functional size may be used:

• to budget application development or enhancement costs
• to budget the annual maintenance costs of the application portfolio
• to determine project productivity after completion of the project
• to determine the Software Size for cost estimating

FPA can also be used to find the testing effort required in the information system;

The formula is Number of Test Cases = (Function Points)^1.2

Function Points measures systems from a functional perspective they are independent of technology. Regardless of language, development method, or hardware platform used, the number of function points for a system will remain constant. The only variable is the amount of effort needed to deliver a given set of function points.

The Five Components of Function Points are

(a) Data Functions        -> Internal Logical Files 
(b) Data Functions        -> External Interface Files 
(c) Transaction Functions -> External Inputs 
(d) Transaction Functions -> External Outputs 
(e) Transaction Functions -> External Inquiries

See also

• Test effort
• Parametric estimating
• COSMIC (Functional Size Measurement)

External links

• Function Point Modeler
• DEFPAG Deutsche Function Point Anwender Group
• IFPUG, International Function Point Users Group.
• NESMA.
• COSMIC homepage.
• Function Point Training Manual
• WinFPA