How does randomization work in a clinical trial?
Randomization is how researchers assign clinical trial participants by chance to different study groups. In most cases a computer program does the assigning. The doctor and the participant do not choose.
In the simplest trial design there are two groups. The investigational group receives the study intervention or drug being tested. The control group receives the standard treatment already used for that cancer.
Randomization is used mostly in later-phase trials, above all phase 3. That is when researchers compare a new treatment head to head against the current standard of care.
The reason for randomizing is to prevent bias. If doctors chose who went into each group, they might put healthier patients in the treatment group without meaning to. That would make the treatment look better than it really is. Assigning people by chance makes it more likely that any difference between the groups comes from the treatment, not from the people in them.
Want the full picture? Read our complete explanation: What Is Randomization in a Clinical Trial?
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