What is randomization?

• A. Assignment by chance to reduce bias.
• B. Assignment by physician preference.
• C. Assignment by patient choice.
• D. Assignment by sponsor.

Answer: (A)

Randomization is the process of assigning participants to treatment groups by chance, giving each person an equal chance of ending up in any group. This approach helps ensure that the groups are comparable at the start of the study, so differences in outcomes are more likely due to the treatment itself rather than preexisting differences between participants. By balancing both known factors (like age or disease severity) and unknown factors across groups, randomization reduces selection bias and confounding, which underpins the validity of statistical comparisons and supports conclusions from intention-to-treat analyses. Methods can include computer-generated random numbers or randomization schemes like blocks or stratification to maintain balance over time or on key characteristics. In contrast, assigning by physician preference, patient choice, or sponsor decisions can introduce bias by allowing systematic differences between groups, which undermines the trial’s ability to attribute outcomes to the treatment.