Robust and efficient designs for the Michaelis-Menten model

For the Michaelis-Menten model we determine designs which maximize the minimum of the D-eÆciencies over a certain interval for the non-linear parameter. The best two point designs can be found explicitly and a characterization is given, when these designs are optimal within the class of all designs. In most cases of practical interest the determined designs are highly eÆcient and robust with respect to misspeci cation of the non-linear parameter. The results are illustrated and applied in an example of hormone-receptor assay.