Determining fault insertion rates for evolving software systems

In developing a software system, we would like to be able to estimate the way in which the fault content changes during its development, as well as determining the locations having the highest concentration of faults. In the phases prior to test, however, there may be very little direct information regarding the number and location of faults. This lack of direct information requires the development of a fault surrogate from which the number of faults and their location can be estimated. We develop a fault surrogate based on changes in relative complexity, a synthetic measure which has been successfully used as a fault surrogate in previous work. We show that changes in the relative complexity can be used to estimate the rates at which faults are inserted into a system between successive revisions. These rates can be used to continuously monitor the total number of faults inserted into a system, the residual fault content, and identify those portions of a system requiring the application of additional fault detection and removal resources