This document focuses on system-initiated and human-initiated transitions (Clause 6) from a higher level to a lower level of automated driving. Human factors and system factors that can influence takeover performance are included (Clauses 7 and 8). Although some are still under investigation, there is a need to appropriately set these factors as variables to better understand their effects or to better control/eliminate their influence. This approach will aid research design by ensuring that important factors are considered and support consistency across studies enabling meaningful comparisons of findings. This document also includes information on considerations in test scenario design (Clause 9), common measures for human takeover performance (Clause 10) and considerations in choosing a testing environment (Clause 11) to help readers design experiments comparable to other studies.