Optimal designs for the exponential model with correlated observations

In the exponential regression model with an autoregressive error structure exact D-optimal designs for weighted least squares analysis are investigated. It is shown that support points of a locally D-optimal design are discontinuous with respect to the correlation parameter. Also equidistant designs are proved to be considerably less efficient than maximin efficient D-optimal designs. A tool used in the study is the functional approach described in a recent book Melas (2006)