An evidence-backed serum has documented study data — participant numbers, duration, and measured outcomes (like hair density or count) — for the finished formula, ideally with institutional oversight, rather than just listing 'clinically proven' ingredients without showing results for the actual finished product. HairReve's DOH-Tondo Medical Center pilot study, for example, tracked 15-18% hair density improvement and a 65% improvement on the Physician's Global Assessment scale over 16 weeks, assessed by three blinded dermatologists.