Hello, I would like to know how may a perform randomization for a future RCT, stratified according to age, sex, and a specific medical condition (that has 3 levels). Aloccation should be into one of 4 groups along the study (each time a participant join, I target to allocate into a group but I do nod have previous knowlegde on the age/sex and medical condition of a future participant).

Thank you very much for your help!