  Software change is the basic task of software evolution and maintenance.
Phased Model for Software Change (PMSC) is a process model for software changes
that localize in the code. It consists of several phases that cover both
program comprehension and code modifications. This paper presents an empirical
study of an enactment of PMSC, enhanced by the use of tool JRipples. The
subjects are graduate students with varying degree of programming experience.
The empirical findings demonstrate that programmers with knowledge of PMSC and
supported by JRipples perform perfective software changes in unfamiliar
software in significantly less time (about half time) than unaided programmers.
Substantial time improvements were witnessed in both code comprehension and
implementation efforts.
