Modeling maintenance effort by means of dynamic systems

The dynamic evolution of ecological systems in which predators and prey compete for survival has been investigated by applying suitable mathematical models. Dynamic systems theory provides a useful way to model interspecies competition and thus the evolution of predators and prey populations. This kind of mathematical framework has been shown to be well suited to describe evolution of economical systems as well, where instead of predators and prey there are consumers and resources. This paper suggests how dynamic systems could be usefully applied to the maintenance context, namely to model the dynamic evolution of the maintenance effort. When maintainers start trying to recognize and correct code defects, while the number of residual defects decreases, the effort spent to find out any new defect has an initial increase, followed by a decline, in a similar way to prey and predator populations. The feasibility of this approach is supported by the experimental data about a 67 months maintenance task of a software project and its successive releases.