The U.S. Food and Drug Administration (FDA) requires pharmaceutical companies to evaluate new drugs through a series of clinical trials . Phase 1 trials assess safety and dosage, and involve 20-100 participants. Phase 2 trials assess efficacy and side effects, and can involve up to several hundred participants. Phase 3 trials assess efficacy and adverse reactions, and typically involve 300-3,000 participants. . Why does the number of study participants increase as a drug moves progressively through the clinical trials? More generally, can you comment on when a small sample would be preferred over a large sample and vice-versa