Page 137 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Unit 6: Effort Estimation

Notes

The Value Adjustment Factor (VAF) is based on 14 General System Characteristics (GSC’s) that
rate the general functionality of the application being counted. Each characteristic has associated
descriptions that help determine the degrees of influence of the characteristics. The degrees of
influence range on a scale of zero to five, from no influence to strong influence. The IFPUG
Counting Practices Manual provides detailed evaluation criteria for each of the GSC’S, the table
below is intended to provide an overview of each GSC.

General System Characteristic Brief Description
1. Data communications How many communication facilities are there to aid in the
transfer or exchange of information with the application or
system?
2. Distributed data processing How are distributed data and processing functions handled?
3. Performance Was response time or throughput required by the user?
4. Heavily used configuration How heavily used is the current hardware platform where the
application will be executed?
5. Transaction rate How frequently are transactions executed daily, weekly,
monthly, etc.?
6. On-Line data entry What percentage of the information is entered On-Line?
7. End-user efficiency Was the application designed for end-user efficiency?
8. On-Line update How many ILF’s are updated by On-Line transaction?
9. Complex processing Does the application have extensive logical or mathematical
processing?
10. Reusability Was the application developed to meet one or many user’s
needs?
11. Installation ease How difficult is conversion and installation?
12. Operational ease How effective and/or automated are start-up, back-up, and
recovery procedures?
13. Multiple sites Was the application specifically designed, developed, and
supported to be installed at multiple sites for multiple
organizations?
14. Facilitate change Was the application specifically designed, developed, and
supported to facilitate change?

Once all the 14 GSC’s have been answered, they should be tabulated using the IFPUG Value
Adjustment Equation (VAF)

14 where: Ci = degree of influence for each General System Characteristic
VAF = 0.65 + [ (Ci) / 100] .i = is from 1 to 14 representing each GSC.
i =1, A = is summation of all 14 GSC’s.

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