5.27 In radioligand binding, two alternative models relating y to x are specified as follows, where α, κ, κ1 and κ2 are parameters.

(i) y = p 1 + 10x−κ1 + (1 − p)

1 + 10(αx−κ2) ,

(ii) y = 1 1 + 10x−κ .

Identify which non-regular problem results when we compare these two models.