Oops!... I did it again. Analysing and Handling Conclusion (In-)Stability in Socio-Technical Software Engineering
Context: Mining software repositories is a popular means to gain insights into a software project's evolution, monitor project health, support decisions and derive best practices. Tools supporting the mining process are commonly applied by researchers and practitioners, but their limitations and agreement are often not well understood. Objective: This study investigates some threats to validity in complex tool pipelines for evolutionary socio-technical software analyses. We evaluate the tools' agreement in terms of data, study outcomes and conclusions for the same research questions to derive actionable advice for researchers and practitioners. Method: We conduct a lightweight literature review to select \emph{three} studies on collaboration and coordination, software maintenance and software quality from high-ranked venues, which we formally replicate with \emph{four} independent, systematically selected mining tools to quantitatively and qualitatively compare the extracted data, analysis results and conclusions. Results: We find and summarise numerous technical details in tool design and implementation which accumulate along the complex mining pipelines and can cause substantial differences in the extracted baseline data, its derivatives, subsequent results of statistical analyses and, under specific circumstances, conclusions. Conclusions: Users should evaluate mining tools and their limitations carefully to scope the validity of their conclusions, for instance with the checklist we provide. Researchers and tool authors can further reduce uncertainty through reproduction packages and comparative studies in other MSR fields following our methodology.