[Background] Recent investigations into the effects of Test-Driven
Development (TDD) have been contradictory and inconclusive. This hinders
development teams to use research results as the basis for deciding whether and
how to apply TDD. [Aim] To support researchers when designing a new study and
to increase the applicability of TDD research in the decision-making process in
the industrial context, we aim at identifying the reasons behind the
inconclusive research results in TDD. [Method] We studied the state of the art
in TDD research published in top venues in the past decade, and analyzed the
way these studies were set up. [Results] We identified five categories of
factors that directly impact the outcome of studies on TDD. [Conclusions] This
work can help researchers to conduct more reliable studies, and inform
practitioners of risks they need to consider when consulting research on TDD.Comment: ESEM '20: ACM / IEEE International Symposium on Empirical Software
Engineering and Measurement (ESEM), October 8--9, 2020, Bari, Ital