Understanding Recurring Software Quality Problems of Novice Programmers

It remains unclear when is the right time to introduce software quality into the computing curriculum. Introductory students often cannot afford to also worry about software quality, while advanced students may have been groomed into undisciplined development practices already. To be able to answer these questions, educators need strong quantitative evidence about the persistence of software quality problems in programs written by novice programmers. This technical report presents a comprehensive study of software quality in programs written by novice programmers. By leveraging the patterns of recurring quality problems, known as code smells, we analyze a longitudinal dataset of more than 100 novice Scratch programmers and close to 3,000 of their programs. Even after gaining proficiency, students continue to introduce certain quality problems into their programs, suggesting the need for educational interventions. Given the importance of software quality for modern society, computing educators should teach quality-promoting practices alongside the core computing concepts.