In This Issue

In this issue we have three regular research papers and a special section on Software Quality for Mobile Apps. The increase in sales and deployment of mobile apps in recent years means that any improvements in their quality will have huge ramifications. Consequently, I am convinced that this special section will be of great interest to many of our readers. I am very grateful to the guest editors, Claudia Iacob, Shamal Faily and David Bell, for all their hard work on the solicitation and reviews of these papers. The guest editors have provided a very helpful introduction to the special section. The regular papers in this issue deal with the disparate topics of defect prediction, testing and systems architecture. In ‘‘Which Process Metrics Significantly Improve Defect Prediction Models across Multiple Projects? An Empirical Study’’, Lech Madeyski and Marian Jureczko compare a number of defect prediction models to determine the effect of including process metrics. The authors conclude that defect prediction models that include process metrics are significantly better than simple models that use only product metrics. Testing is a crucial part of software development. The paper ‘‘Fault Domain-Based Testing in Imperfect Situations: A Heuristic Approach and Case Studies’’ by Fevzi Belli, Mutlu Beyazıt, Andre Takeshi Endo, Aditya Mathur and Adenilso Simao proposes a heuristic method, called Heuristic Harmonized State Identifiers, based on a finite state machine. The method generates test sets that cover all faults in a given domain under certain conditions. The method is validated using case studies. The results show that the proposed method detects more faults than other methods and achieves better fault detection rates than random testing with equivalent test execution effort. The architectural stage of systems design is extremely important because errors made during this stage are very difficult to correct once detailed design and implementation have