function point analysis & estimation

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www.davidconsultinggroup.com

FUNCTION POINT ANALYSIS &

ESTIMATION

Gurpreet Singh

M.Tech CSE Part Time – 3rd Semester

Roll No. 17 & Regd. No. 40800066


What is Function Point Analysis (FPA)?

• It is designed to estimate and measure the time, and thereby the cost, of developing new software applications and maintaining existing software applications.

• It is also useful in comparing and highlighting opportunities for productivity improvements in software development.

• It was developed by A.J. Albrecht of the IBM Corporation in the early 1980s.

• The main other approach used for measuring the size, and therefore the time required, of software project is lines of code (LOC) – which has a number of inherent problems.


• Inputs• Outputs• Inquiries• Internal Logical Files• External Interface Files

Input Inquiry

Output

InternalLogical

Files

External Interface

File

Five key components are identified based on logical user view

Application

The Function Point Methodology


General System CharacteristicsData Communication On-Line Update

Distributed Data Processing Complex Processing

Performance Objectives Reusability

Heavily Used Configuration Conversion & Install Ease

Transaction Rate Operational Ease

On-Line Data Entry Multiple-Site Use

End-User Efficiency Facilitate Change

The final calculation is based upon the Unadjusted FP count X VAF

14 Optional General Systems Characteristics are evaluated and used to compute a Value Adjustment Factor (VAF)

The Function Point Methodology



These function-point counts are then weighed (multiplied) by their degree of complexity:

Simple Average ComplexInputs 2 4 6Outputs 3 5 7Files 5 10 15Inquires 2 4 6Interfaces 4 7 10



A simple example:

inputs3 simple X 2 = 6 4 average X 4 = 161 complex X 6 = 6

outputs6 average X 5 = 302 complex X 7 = 14

files5 complex X 15 = 75

inquiries8 average X 4 = 32

interfaces3 average X 7 = 214 complex X 10 = 40

Unadjusted function points 240



Continuing our example . . . Complex internal processing = 3Code to be reusable = 2High performance = 4Multiple sites = 3Distributed processing = 5

Project adjustment factor = 17

Adjustment calculation:Adjusted FP = Unadjusted FP X [0.65 + (adjustment factor X 0.01)] = 240 X [0.65 + ( 17 X 0.01)] = 240 X [0.82] = 197 Adjusted function points


PROJECTSIZE

X X RISKFACTORS

PROJECTCOMPLEXITY

DEFINITION CAPABILITY ESTIMATE

Schedule

Effort Costs

REQUIREMENT

FUNCTION POINT ANALYSIS

Project Estimation


Conclusions

• Project Management can be successful • Requirements can be managed • Projects can be sized • Performance can be successfully estimated • Process improvement can be modeled• Measurement can be accomplished


Thanks

function point analysis & estimation

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