Stochastic processes observed over space often exhibit nonstationarity. Possible causes of nonstationarity include mean drift, heterogeneity of responses, or a correlation pattern that is not simply a function of the Euclidean distance between two spatial locations. This paper considers the...

Ford and Silvey [(1980) A sequentially constructed design for estimations a nonlinear parametric function. Biometrika 67, 381-388] conjectured that the usual asymptotic confidence interval arising from a sequential design based on a nonlinear model has the same asymptotic properties as it would...