31 Function Point Analysis – Lecture II

In employee tracking system ETS is a basic employee attendance system planned to serve small to medium-sized businesses employing 10–100 employees. The system is planned to have interfaces to the company’s other software packages: Human-Master, which serves human resources units, and Wage-Master, which serves the wages units. ETS is planned to produce several reports and online queries.

 

In step 1 of function point analysis it determines the following components

 

  • EI: External Inputs
  • EO: External Outputs
  • EQ: External Queries
  • ILF: Internal Log Files
  • ELF: External Log Files

Analysis of the software system as presented in the DFD summarizes the number of the various components:

 

  • Number of user inputs (EI) – 2
  • Number of user outputs (EO) – 3
  • Number of user online queries (EQ) – 3
  • Number of logical files (ILF) – 2

The degree of complexity (simple, average or complex) was evaluated for each component.

 

In step 2 compute the unadjusted function point (UFP) which rate each component as low, average, or high. For transactions (EI, EO, and EQ), the rating is based on the FTR and DET.

  • EI-External Inputs
  • EO-External outputs
  • EQ-External Queries
  • FTR – The number of files updated or referenced.
  • DET – The number of user-recognizable fields.

For files (ILF and ELF), the rating is based on the RET and DET. RET – The number of user-recognizable data elements in an ILF or ELF. DET – The number of user-recognizable fields.

  • ILF – Internal Logic File.
  • ELF – External Logic File.

In step 3 of function point analysis Compute Value Adjustment Factor (VAF) based on 14 general system characteristics (GSC). Weight each GSC on a scale of 0 to 5 based on whether it has no influence to strong influence.

 

In Employee Tracking System:

In step 4 compute the Function point as follows: Compute the FP as follows.

 

VAF=sum (GSC)

 

FP = UFP * (0.65 + (VAF* .01))

  • GSC-General System Characteristics
  • FP – Function Point
  • VAF – Value Adjustment Factor
  • UFP-Unadjusted Function Point

Summary

 

The steps involved in Function Point Analysis are:

 

  1. Determine the Components
  • EI: External Input
  • EO: External Outputs
  • EQ: External Queries
  • ILF: Internal Log Files
  • ELF: External Log File

2. Compute the Unadjusted Function Point (UFP).

3.Compute Value Adjustment Factor (VAF) based on 14 general system characteristics (GSC).

4.Calculate the final Function Point.

 

Function point Analysis for a case study “Employee Tracking System ( ETS ) “ has been illustrated in this lecture. In this Case study, Unadjusted Function Point (UFP) is refined by using Value Adjustment Factor (VAF).