Use case point analysis - a software estimation technique

The number of use case points of a project is dependent on following factors.

1. The number and complexity of use cases in the application system.
2. The number and complexity of actors in the system.
3. Some non-functional attributes like portability, performance, scalability etc.
4. Environmental factors team’s experience and team motivation.

Complexity of a use case is defined as simple, average or complex depending on the number of transactions in the use case. Extension transaction which starts with result of another transaction shouldn’t be counted usually. Use case points are assigned to a use case based the complexity of the use case as listed in below table.

Unadjusted Use Case Weight
Use Case Complexity	No of Transaction	Weight
Simple	3 or fewer	5
Average	4-7	10
Complex	7 or more	15

Use case points for a use case actor are calculated per below summarized description in below table.

Unadjusted Actor Weight
Actor Type	Example	Weight
Simple	Another System Through API	1
Average	Another System through a protocol, a person through text-base user interface	2
Complex	A person through a graphical user interface	3

Total unadjusted use case point for a software project is calculated as summation of use case point and actor points as shown in below table.

Unadjusted Use Case Point
Sl No	Name	Use Case/Actor	Complexity	Number	Weight	Number*Weight
1	Use Case 1	Use Case	Average	2	10	20
2	Use Case 2	Use Case	Complex	3	15	45
3	Use Case 3	Use Case	Simple	6	5	30
4	Actor 1	Actor	Average	21	2	42
5	Actor 2	Actor	Complex	9	3	27
Total						164

There are 13 parameters in technical complexity with different weight value as listed in fig 4. These factors are assessed to a value between 0-5 depending on individual project requirement. The final technical complexity factor is calculated as TCF = 0.6 + (0.01 * TFactor).

Technical Complexity Factor
Factor	Weight	Assessment(0-5)	Impact
Distributed system	2	0	0
Performance objectives	2	1	2
End-user efficiency	1	3	3
Complex processing	1	4	4
Reusable code	1	4	4
Easy to install	0.5	1	0.5
Easy to use	0.5	1	0.5
Portable	2	4	8
Easy to change	1	5	5
Concurrent use	1	5	5
Security	1	5	5
Access for 3rd party	1	5	5
Training Needs	1	1	1
Total (TFacor)			43

There are 8 parameters in environment complexity with different weight value as listed in fig 5. These factors are assessed to a value between 0-5 depending on the environment in which project is executed. The final environment factor is calculated as EF = 1.4 + (-0.03 * EFactor).

Environment Factor
Factor	Weight	Assessment(0-5)	Impact
Familiar with the development process	1.5	1	1.5
Application experience	0.5	3	1.5
Object-oriented experience	1	2	2
Lead analyst capability	0.5	5	2.5
Motivation	1	2	2
Stable requirements	2	1	2
Part-time staff	-1	1	-1
Difficult programming language	-1	3	-3
Total (EFacor)			7.5

And, finally total use case point of a software project is UUCW*TCF*EF where UUCW is unadjusted use case weight, TCF technical complexity factor and EF is environment factor.