Table 2.

Maximum likelihood estimates (MLEs) and estimated standard errors (S.E.s) under the Hill model, expressed in terms of either dose or the natural logarithm of dose, for the data of Jeske et al (2009) on the effect of selenocysteine on the death rates of flies.

Hill model (1), in terms of dose di				Hill model (2), in terms of zi = ln(di)
Parameter	MLE	S.E.		Parameter	MLE	S.E.
ϕ1 (min)	0.033	0.010		γ (min)	0.033	0.010
ϕ2 (max)	0.673	0.115		δ (max–min)	0.641	0.118
ϕ3 (ED50)	55.962	9.392		α (intercept)	−13.368	3.923
ϕ4 (shape)	3.322	1.084		β (slope)	3.322	1.084

The parameterizations are related as follows: ϕ₁ = γ, ϕ₂ = γ + δ, ϕ₃ = exp(−α/β), ϕ₄ = β.