The concept of UCP is based on the requirements for the system being written using use cases, which is part of the UML set of modeling techniques.
The software size (UCP) is calculated based on elements of the system use cases with factoring to account for technical and environmental considerations.
The UCP technique was developed by Gustav Karner in 1993 while employed at what was known at the time as Objectory Systems, which later merged into Rational Software and then IBM.
The UCP method was created to solve for estimating the software size of systems that were object oriented.
The TCF is one of the factors applied to the estimated size of the software in order to account for technical considerations of the system.
The TF is then used to compute the TCF with the following formula: The ECF is another factor applied to the estimated size of the software in order to account for environmental considerations of the system.
The Online Shopping System use case diagram is depicting five actors; One simple for the Payment Processing System and four complex for each of the human users actors (i.e. Online Customer, Marketing Administrator, Warehouse Clerk, Warehouse Manager.)
One major weakness of the Use Case Points method is that it has never been thoroughly calibrated using regression analysis due to a lack of a statistically sufficient number of projects.
Moreover, the linear model of Karners approach does not take the diseconomies of scale into account that occur in software development projects.
[4] Still, the easily applicable sizing approach and counting rules provide many benefits for estimations in early phases and thus allow to quickly yield the FSM (functional size measurement, in this case UUCW + UAW) of an application or IT product.