Software Estimation Techniques

Software Estimation Techniques By: Kamalmeet Singh

What is Software Estimation?
How much resources?
How much time?
How much effort?
How much Cost?

Why do we need it?
Would you like to start creating something without knowing the cost?
Will it be better to buy/outsource than create?

Difficulties
Premature estimations, if you don’t have the complete details
Lack of Historical data
Failure to follow the estimates: conditions prescribed in the estimate must not be violated
Failure to update the estimates

How to do it?

Factors to be considered
Product Objectives
Corporate Assets
Project Constraints

Product Objectives
Scope:
Capabilities to be provided by the software
Quality:
Performance
Resource usage
Compatibility with h/w and s/w
Factors like – usability, security, safety, reliabilty and transportability

Corporate Assets
People
Process models
Development tools
Reusable software components
Policies and procedures
Workplace environment

Project Constraints
Design constraints
Compatibility with h/w and s/w
Memory and timing
Implementation language
Process constraints
Number and type of people
Development environment
Scheduled delivery date

What do we need to calculate?
LOC
(Lines Of Code)
Or
FP
(Function Points)

Function Point Analysis
Function point count= UFP * VAM
UFP: Unadjusted Function Point
VAM: Value Adjustment Multiplier

Unadjusted FP (UFPs)
1. External Inputs - data or control inputs (input files, tables, forms, screens, messages, etc.) to the system
2. External Outputs - data or control outputs from the system
3. External Inquiries - I/O queries which require a response (prompts, interrupts, calls, etc.)
4. External Interfaces - libraries or programs which are passed into and out of the system (I/O routines, sorting procedures, math libraries, run-time libraries, etc.)
5. Internal Data Files - groupings of data stored internally in the system (entities, internal control files, directories)

UFP metrics

Value Adjustment Factors
1. data communications
2. distributed functions
3. performance
4. heavily used operational configuration
5. transaction rate
6. on-line data entry
7. design for end user efficiency
8. on-line update of logical internal files
9. complex processing
10. reusability of system code
11. installation ease
12. operational ease
13. multiple sites
14. ease of change

Value Adjustment Multiplier
0 - factor not present or has no influence
1 - insignificant influence
2 - moderate influence
3 - average influence
4 - significant influence
5 - strong influence

Calculating Effort
Effort in Person Month
For LOC
E=5.2 * (KLOC)^0.91 [waltson-Felix model]
E=5.5 + 0.73 * (KLOC)^1.16 [Bailey Basili model]
E=3.2 * (KLOC)^1.05 [Boehm simple model]
E=5.288 * (KLOC)^1.047 [Doty model for KLOC>9]
For FP
E=-13.39 + 0.0545 FP [Albert and Gaffney model]
E=60.62 * 7.728 * 10^-8 FP^3 [Kermer model]
E=585.7 +15.12 FP [Matso, Barnett and Mellichamp model]

Models for Cost Estimation
SDM- Software Development Model
SLIM- Software Lifecycle Management
COCOMO- Constructive Cost Model
COCOMO II- COCOMO next version
COPMO- Cooperative Programming Model

Basic COCOMO Model
Organic projects - are relatively small, simple software projects in which small teams with good application experience work to a set of less than rigid requirements.
Semi-detached projects - are intermediate (in size and complexity) software projects in which teams with mixed experience levels must meet a mix of rigid and less than rigid requirements.
Embedded projects - are software projects that must be developed within a set of tight hardware, software, and operational constraints.

Basic COCOMO
E=a(KLOC)^b
D=c(E)^d
P=E/D
E- effort
D- development time
P- number of people
Software project a b c d
Organic 2.4 1.05 2.5 0.38
Semi-detached 3.0 1.12 2.5 0.35
Embedded 3.6 1.20 2.5 0.32

Intermediate COCOMO
E= a( KLOC)^ (b) * EAF
Software project a b
Organic 3.2 1.05
Semi-detached 3.0 1.12
Embedded 2.8 1.20
EAF: Effort Adjustment Factor

Conclusion

Questions?

Thank You

http://www.slideshare.net	289
http://www.kamalmeet.com	74
http://testingbaires.com	40
http://kamalmeet.com	34
http://charithw.blogspot.com	15
http://static.slidesharecdn.com	7
http://www.scoop.it	5
http://www.lmodules.com	1
http://webcache.googleusercontent.com	1
http://www.charithw.blogspot.com	1

Software Estimation Techniques

by kamal on Apr 18, 2007

Accessibility

Categories

Tags

Upload Details

Usage Rights

10 Embeds 467

Statistics

Software Estimation Techniques — Presentation Transcript