  Context: Software Engineering (SE) experiments suffer from threats to
validity that may impact their results. Replication allows researchers building
on top of previous experiments' weaknesses and increasing the reliability of
the findings. Objective: Illustrating the benefits of replication to increase
the reliability of the findings and uncover moderator variables. Method: We
replicate an experiment on Test-Driven-Development (TDD) and address some of
its threats to validity and those of a previous replication. We compare the
replications' results and hypothesize on plausible moderators impacting
results. Results: Differences across TDD replications' results might be due to
the operationalization of the response variables, the allocation of subjects to
treatments, the allowance to work outside the laboratory, the provision of
stubs, or the task. Conclusion: Replications allow examining the robustness of
the findings, hypothesizing on plausible moderators influencing results, and
strengthening the evidence obtained.
