Randomization

What does Randomization mean in clinical research?

ICH E6(R3) defines randomization as the process of deliberately including an element of chance when assigning participants to groups that receive different treatments, in order to reduce bias.^⁠[1] Because neither the investigator nor the participant chooses the group, differences in outcomes can be attributed to the treatment rather than to who was picked for it. Methods include simple, block and stratified randomization, often run through an interactive response system.

Randomization is also the line between screening and enrollment in many protocols. A GSK protocol posted on ClinicalTrials.gov, for example, defines screen failures as participants who consent to participate but are not subsequently randomized.^⁠[2] Enrollment targets, per-patient payments and site rankings are often counted at this milestone.

Practical note: agree with the sponsor, and with any recruitment vendor, on exactly what counts as enrolled before the study starts. Bond's performance fee is charged per enrolled patient, defined as successfully randomized, so payment follows the same milestone sponsors count. See Pricing.