Fitting parametric link functions in generalised linear models

Abstract In a generalised linear model the mean of each observation is assumed to be related to its linear predictor by a known link function. In some cases this link function may not be known exactly, but can be assumed to be of some general ‘parametric’ form. We show how generalised linear models can be extended to fit models with such link functions. Examples given include the two-parameter logistic and estimating the exponent of the Box-Cox link. GLIM-3 coding is supplied.