  Object-oriented software metrics provide a numerical characterization of
software quality. They have also been used in the assessment and identification
of technical debt. However, metrics generally need to be used with thresholds
as reference points that help to interpret their values properly and
objectively. The problem is that, while there are many proposed metrics, there
are relatively few studies on thresholds and threshold calculation methods;
hence, the effective application of metrics in practice has been limited.
Moreover, although it has been acknowledged that thresholds should not be
absolute, but rather relative to certain contextual factors, the context is
still not considered in most threshold studies. In this paper, the relationship
between system size (as a contextual factor) and metric thresholds is
investigated. The objective is to build predictive models that estimate
thresholds based solely on system size, and to assess the feasibility of this
approach as a threshold estimation method. An empirical study is conducted for
this purpose using 36 defect-prediction datasets and six metrics. The results
show that the proposed threshold estimation method is feasible, and it can
achieve an accuracy remarkably comparable to more complex threshold models.
