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In a manual examination of more than 7,000 issue reports from the bug databases of five open-source projects, we found 33.8% of all bug reports to be misclassified - that is, rather than referring to a code fix, they resulted in a new feature, an update to documentation, or an internal refactoring. This misclassification introduces bias in bug prediction(More)
In software development, every change induces a risk. What happens if code changes again and again in some period of time? In an empirical study on Windows Vista, we found that the features of such change bursts have the highest predictive power for defect-prone components. With precision and recall values well above 90%, change bursts significantly(More)
When interacting with version control systems, developers often commit unrelated or loosely related code changes in a single transaction. When analyzing the version history, such tangled changes will make all changes to all modules appear related, possibly compromising the resulting analyses through noise and bias. In an investigation of five open-source(More)
Several defect prediction models have been proposed to identify which entities in a software system are likely to have defects before its release. This paper presents a replication of one such study conducted by Zimmermann and Nagappan on Windows Server 2003 where the authors leveraged dependency relationships between software entities captured using social(More)
By integrating various development and collaboration tools into one single platform, the Jazz environment offers several opportunities for software repository miners. In particular, Jazz offers full traceability from the initial requirements via work packages and work assignments to the final changes and tests; all these features can be easily accessed and(More)
When analyzing version histories, researchers traditionally focused on single events: e.g. the change that causes a bug, the fix that resolves an issue. Sometimes however, there are indirect effects that count: Changing a module may lead to plenty of follow-up modifications in other places, making the initial change having an impact on those later changes.(More)
Software reliability is heavily impacted by software changes. ow do these changes relate to each other? By analyzing the impacted method definitions and usages, we determine dependencies between changes, resulting in a change genealogy that captures how earlier changes enable and cause later ones. Model checking this genealogy reveals temporal process(More)
Which components of a large software system are the most defect-prone? In a study on a large SAP Java system, we evaluated and compared a number of defect predictors, based on code features such as complexity metrics, static error detectors, change frequency, or component imports, thus replicating a number of earlier case studies in an industrial context.(More)
Testing is a key element of software development processes for the management and assessment of product quality. In most development environments, the software engineers are responsible for ensuring the functional correctness of code. However, for large complex software products, there is an additional need to check that changes do not negatively impact(More)