“…Although expenditure on software development increases by 200% each decade, productivity of software system engineers only increases by 35% (Leon, 2004). Approximately 75% of the total life cycle cost for a given system is related to system maintenance and operation (Jorgensen and Molokken-Ostvold, 2006;Gilb, 2006;Standish Group, 2014a;Standish Group, 2014b;Cerpa and Verner, 2009;Linberg, 1999;Chen and Huang, 2009;Tang and Huang, 2011). Technical debt has been recognized as a critical factor that leads to the escalating maintenance cost of software systems.…”