Question 1 of 9 Fundamentals Concept
What is the purpose of randomization in a trial?
Short answer
Randomization uses a chance mechanism to assign treatment, reducing systematic differences between groups and supporting causal comparison. It does not guarantee balance in every sample. Allocation concealment protects the assignment process, while blinding addresses knowledge of the treatment after allocation.
Why
Randomization is a way to reduce allocation-related confounding. Because assignment is governed by chance, treatment groups are comparable in expectation for measured and unmeasured pre-treatment factors, though an individual small trial can still have imbalances. This is different from random sampling, which determines who is invited into the study and affects generalizability.
A proper workflow creates a valid random sequence, conceals future allocations during enrollment and documents who generated, implemented and received assignments. For example, a centrally managed system can assign a participant after eligibility is confirmed. Blocking or stratification may help balance important prognostic factors, but their use and analysis must be prespecified.
Blinding then helps reduce expectation and measurement biases after allocation. If recruiters can predict the next assignment, they may selectively enroll participants and undermine the randomization. The goal is not identical baseline tables.
It is a defensible process for unbiased treatment comparison supported by complete and transparent follow-up.
A strong answer covers
- Distinguish randomization from blinding