 Restricted randomization

Restricted randomization samples assignments from a specified subset preserving features such as block balance, fixed group sizes or allowable treatment sequences. Inference must respect the chosen allocation scheme rather than treating all label permutations as admissible.

Restricted randomization refers to a method used in experimental design, particularly in randomized controlled trials (RCTs), where certain constraints or rules are applied to the random assignment of participants to different treatment groups. This approach helps ensure that specific characteristics are balanced across groups while still maintaining an element of randomness. Some common forms of restricted randomization include: 1. **Stratified Randomization**: Participants are divided into subgroups (strata) based on certain characteristics (e.g.