Sigmoidal Emax Model E = Emax · C^n / (EC50^n + C^n) With competitive antagonist (Schild): EC50_apparent = EC50 · (1 + [B]/KB) where KB = 10^(-pA2) Receptor Occupancy: RO = C^n / (EC50^n + C^n) · 100% pA2 = -log10(KB) KB = [antagonist] producing 2× EC50 shift