  To effectively manage Technical Debt (TD), we need reliable means to quantify
it. We conducted a Systematic Mapping Study (SMS) where we identified TD
quantification approaches that focus on different aspects of TD. Some
approaches base the quantification on the identification of smells, some
quantify the Return on Investment (ROI) of refactoring, some compare an ideal
state with the current state of a software in terms of the software quality,
and some compare alternative development paths to reduce TD. It is unclear if
these approaches are quantifying the same thing and if they support similar or
different decisions regarding TD Management (TDM). This creates the problem of
not being able to effectively compare and evaluate approaches. To solve this
problem, we developed a novel conceptual model, the Technical Debt
Quantification Model (TDQM), that captures the important concepts related to TD
quantification and illustrates the relationships between them. TDQM can
represent varied TD quantification approaches via a common uniform
representation, the TDQM Approach Comparison Matrix, that allows performing
useful comparisons and evaluations between approaches. This paper reports on
the mapping study, the development of TDQM, and on applying TDQM to compare and
evaluate TD quantification approaches.
