How does COSMIC work?
While the Expert Judgement or Story Points estimation methods rely on the expert’s “feeling” to determine how long it would take to deliver a particular requirement, COSMIC uses a more standardised way to describe the size of the software. The idea behind COSMIC is that no matter who performs the estimation, the result will always be the same. To achieve that, a framework has been developed.
This framework describes the whole estimation process and the convention of names, rules and principles on how to approach measuring the size of the software and ultimately – the cost of building it. The result of the measurement process is an amount of COSMIC Functional Points (CFP).
A CFP is defined as one unit of “data movement” which can be one of the following:
The basic idea behind the COSMIC method is to identify all data movements, classify them as one of the above types, then add them up to calculate the size of the software and its components. Translating this to software requirements, each requirement has at least two points – Entry and Exit.
While adding up the identified points is relatively easy, the bigger challenge is to unify the requirements in a way that enables you to label every data movement.
Piotr Pozniak