Biometrical Letters Vol. 44(2), 2007, pp. 85-96
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A-OPTIMAL DESIGNS UNDER A QUADRATIC GROWTH CURVE MODEL IN THE TRANSFORMED TIME INTERVAL Katarzyna Filipiak, Anna Szczepańska Department of Mathematical and Statistical Methods Agricultural University of Poznań Wojska Polskiego 28, 60-637 Poznań Poland; e-mail: kasfil@au.poznan.pl e-mail: sanna6@wp.pl |
In this paper the quadratic growth curve model with correlated observations is considered. For a symmetric experimental domain we determine a scale alfa>0 and a correlation structure such that the A-optimal design over the time interval [-1,1] is also optimal over [-alfa, alfa]. For some correlation structures the design d*={-alfa,0,alfa}is A- and D-optimal over [-alfa,alfa]. Therefore the second aim of this paper is to determine an asymmetric experimental domain [alfa, beta] and correlation structure such that the design d={alfa, (alfa+beta)/2, beta} which is D-optimal over [alfa, beta] is also A-optimal.
growth curve model, A-optimal design.
