Maximin and maximin-efficient event-related fMRI designs under a nonlinear model
Ming-Hung Kao, Dibyen Majumdar, Abhyuday Mandal, John Stufken
The Annals of Applied Statistics · 2013 · Volume 7 · Issue 4
Abstract
Previous studies on event-related functional magnetic resonance imaging experimental designs are primarily based on linear models, in which a known shape of the hemodynamic response function (HRF) is assumed. However, the HRF shape is usually uncertain at the design stage. To address this issue, we consider a nonlinear model to accommodate a wide spectrum of feasible HRF shapes, and propose efficient approaches for obtaining maximin and maximin-efficient designs. Our approaches involve a reduction in the parameter space and a search algorithm that helps to efficiently search over a restricted class of designs for good designs. The obtained designs are compared with traditional designs widely used in practice. We also demonstrate the usefulness of our approaches via a motivating example.
Keywords
A-optimality, cyclic permutation, design efficiency, Genetic algorithms, hemodynamic response function, information matrix
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