“…An A-optimal design minimizes the trace of the inverse of the Fisher information matrix (FIM) on the unknown parameters, whereas E-, T-and D-optimal designs maximize the smallest eigenvalue, the trace and the determinant of the FIM, respectively (see, e.g., Pukelsheim, 1993;Abt and Welch, 1998;Pázman, 2007). The latter design criterion for regression experiments has been studied by several authors both in uncorrelated (see, e.g., Silvey, 1980) and in correlated setups (Müller and Stehlík, 2004;Kiseľák and Stehlík, 2008;Zagoraiou and Baldi Antognini, 2009;Dette et al, 2015). However, there are several situations when D-optimal designs do not exist, for instance, if one has to estimate the covariance parameter(s) of an Ornstein-Uhlenbeck (OU) process (Zagoraiou and Baldi Antognini, 2009) or sheet (Baran et al, 2015).…”