Randomly assigning individuals to treatment groups ensures that the only difference between the groups is due to the treatment.

The claim states a foundational methodological principle of experimental research: random assignment is designed to eliminate confounding by ensuring that the only systematic difference between treatment groups is the intervention itself. The retrieved literature (such as papers 6 and 7) explicitly supports this by discussing randomized controlled trials as the gold standard for generating causal evidence due to their rigorous methodology for handling confounding. No papers refute this fundamental tenet of experimental design.