Evaluating Software Maintenance Effort: The COME Matrix

If effort estimates are not easily assessed upfront by software maintainers we may have serious problems with large maintenance projects, or when we make repeated maintenance changes to software. This is particularly problematic when inaccurate estimates of the required resources leads to serious negotiation issues. The development of a Categorisation of Maintenance Effort (COME) matrix enables an overall summary of software maintenance changes and maintenance effort to be shown, upfront, to software practitioners. This can occur without any consideration or use of other effort estimation techniques whose results, when used to estimate effort, can appear complicated and it may not be clear how accurate their estimates may be.

We use a simple approach to categorizing maintenance effort data using five steps. We use regression analysis with Jorgensen’s 81 datasets to evaluate the selected variables to find out the true efficacy of our approach: 1) adaptive changes and functional changes with maintenance effort predicted from low to high, 2) high predicted effort when updating KSLOC for software maintenance changes, 3) find that more lines of source codes do not imply that more software maintenance effort is needed, 4) find no significant relationship when we consider the age of the application and 5) find that at least 20 application sizes between KSLOC of 100, 200, 400 and 500 have a low predicted software maintenance effort.

Our experiment shows that using the COME matrix is an alternative approach to other cost estimation techniques for estimating effort for repeated requirement changes in large software maintenance projects.