Toward understanding the rhetoric of small source code changes

Understanding the impact of software changes has been a challenge since software systems were first developed. With the increasing size and complexity of systems, this problem has become more difficult. There are many ways to identify the impact of changes on the system from the plethora of software artifacts produced during development, maintenance, and evolution. We present the analysis of the software development process using change and defect history data. Specifically, we address the problem of small changes by focusing on the properties of the changes rather than the properties of the code itself. Our study reveals that 1) there is less than 4 percent probability that a one-line change introduces a fault in the code, 2) nearly 10 percent of all changes made during the maintenance of the software under consideration were one-line changes, 3) nearly 50 percent of the changes were small changes, 4) nearly 40 percent of changes to fix faults resulted in further faults, 5) the phenomena of change differs for additions, deletions, and modifications as well as for the number of lines affected, and 6) deletions of up to 10 lines did not cause faults.