Dette, HolgerKiss, Christine2012-01-302012-01-302012-01-30http://hdl.handle.net/2003/2929510.17877/DE290R-3273In this paper we consider locally optimal designs problems for rational regression models. In the case where the degrees of polynomials in the numerator and denominator differ by at most 1 we identify an invariance property of the optimal designs if the denominator polynomial is palindromic, which reduces the optimization problem by 50%. The results clarify and extend the particular structure of locally c-, D- and E optimal designs for inverse quadratic regression models which have recently been found by Haines (1992) and Dette and Kiss (2009). We also investigate the relation between the D-optimal designs for the Michaelis Menten and EMAX-model from a more general point of view.enDiscussion Paper / SFB 823;5/2012Chebyshev systemsoptimal designspalindromic polynomialsrational regression models310330620working paper