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 change impact from the plethora of software artifacts produced during development and maintenance. We present the analysis of the software development process using change and defect history data. Specifically, we address the problem of small changes. The studies revealed that (1) there is less than 4 percent probability that a one-line change introduce an error in the code: (2) nearly 10 percent of all changes made during the maintenance of the software under consideration were one-line changes; (3) the phenomena of change differs for additions, deletions and modifications as well as for the number of lines affected.