(16)To enable investment firms to continuously assess whether they obtain the best possible result for their clients on a consistent basis, thus delivering on the best execution requirement, investment firms should assess the relevance of the thresholds that they have determined to ensure such best possible result, including minimum targets and acceptable deviations, per class of financial instrument. To perform a holistic assessment of deviations, investment firms should also account for any relevant differences in execution costs between the venue where the order is executed and the venues included in the reference data.