example, rich people wear fancy clothes. Would distributing fancy clothes to poor people make them rich? This is a case where correlation (between clothes and wealth) does not imply causation.
Harvard graduates get great jobs. Is Harvard good at teaching – or just at selecting smart people who would have done well in life anyway? This is the problem of selection bias.RCTs address these problems by randomly assigning those participating in the trial to receive either a “treatment” or a “placebo” (thereby creating a “control” group). By observing how the two groups differ after the intervention, the effectiveness of the treatment can be assessed. RCTs have been conducted on drugs, micro-loans, training programs, educational tools, and myriad other interventions.