Assigning participants to study groups purely by chance to avoid bias.
Randomisation is the process of allocating trial participants to intervention or control groups using a chance-based method, so that known and unknown confounders are distributed evenly across groups. Proper randomisation (e.g. computer-generated sequences) differs from pseudo-randomisation (e.g. alternation, date of birth), which is more susceptible to selection bias. The quality of randomisation and whether allocation was adequately concealed are key determinants of a trial's internal validity.
This guide was auto-drafted and is pending editorial review.