The Broken Windows Theory Applies to Technical Debt
share
Context: The term technical debt (TD) describes the aggregation of sub-optimal solutions that serve to impede the evolution and maintenance of a system. Some claim that the broken windows theory (BWT), a concept borrowed from criminology, also applies to software development projects. The theory states that the presence of indications of previous crime (such as a broken window) will increase the likelihood of further criminal activity; TD could be considered the broken windows of software systems. Objective: To empirically investigate the causal relationship between the TD density of a system and the propensity of developers to introduce new TD during the extension of that system. Method: The study used a mixed-methods research strategy consisting of a controlled experiment with an accompanying survey and follow-up interviews. The experiment had a total of 29 developers of varying experience levels completing a system extension tasks in an already existing systems with high or low TD density. The solutions were scanned for TD. Six subjects participated in follow-up interviews, where the results were analyzed using thematic analysis. Result: The analysis revealed significant effects of TD level on the subjects' tendency to re-implement (rather than reuse) functionality, choose non-descriptive variable names, and introduce other code smells, all with at least 95 least partially, aware of when they had introduced TD. Conclusion: Three separate significant results along with a validating qualitative result combine to form substantial evidence of the BWT's applicability to software engineering contexts. Existing TD has a major impact on developers propensity to introduce new TD of various types during development. While mimicry seems to be part of the explanation it can not alone describe the observed effects.
READ FULL TEXT