Which concept ensures that trial results are not biased by the method of assigning participants to groups?

• A. QA
• B. Randomization
• C. Protocol Amendment
• D. SAE

Answer: (B)

Preventing bias in how participants are placed into treatment groups. Randomization assigns participants to arms by chance, so the investigators cannot influence who receives the experimental vs control intervention. This creates comparable groups on known and unknown factors, making it more likely that differences in outcomes reflect the intervention rather than preexisting differences, which preserves the study’s internal validity. In contrast, questions about quality assurance focus on processes, protocol amendments are changes to the plan, and SAE refers to serious adverse events—none of these specifically address avoiding bias in group assignment.