One major down side of many defect prediction models is the frequent usability. As an example: A prediction model based on code metrics only, predicts the number of defects based upon the code complexity of each entity. Now, if the programmer fixes the bug, he might change only one line and therefore does not change the code complexity significantly. The complexity might even increase. Using the same defect prediction model again gives us the same result, because the basis of the defect prediction model did not changed or did not changed significantly.
To overcome such problems, we could use a dynamic approach. But most dynamic approaches cannot predict any defects before defects have been discovered.
The idea is to use different time related properties of a code entity to determine the age of this entity. The main assumption is that older entities have fewer defects. Defining the term older entities is the main task of this project.