Table 2.

Dixon’s method and isotonic regression

Drug dose (μg/kg)	Group Y (n = 22)	Group O (n = 20)
Dixon’s method
ED50 (95% C.I.)	0.35 (0.35-0.45)	0.25 (0.15-0.35)
Isotonic regression method
ED50 (83% C.I.)†	0.41 (0.38-0.45)	0.24 (0.19-0.3)
ED95 (95% C.I.)‡	0.57 (0.49-0.59)	0.38 (0.29-0.39)

ED₅₀; 50% effective dose, ED₉₅; 95% effective dose, C.I.; confidence interval Dixon’s method p value (non-parametric): 0.009.

†Isotonic regression method 83% Confidence interval: do not overlap.

‡Isotonic regression method 95% Confidence interval: do not overlap.