Adaptive designs for quantal dose-response experiments with false answers

In psychophysical experiments with quantal dose-response a common problem is the occurrence of lapses due to inattention or, as in forced choice experiments, the occurrence of incorrect guesses—or both. For these situations an optimized sequential design is proposed based on the Fisher information evaluated at the maximum likelihood estimate. This sequential design is compared to the classical Robbins–Monro method of stochastic approximation and modifications thereof in the original nonparametric approach, as well as adapted to the current model with false answers and to Wu’s (1985) original method based on the maximum likelihood estimate by means of a simulation study. In these simulations the optimized sequential design turns out to perform substantially better than its nonparametric competitors, in particular, in the situation of starting points (initial guesses of the parameter of interest) that are far from the true value. Overall, the optimized version also outperforms the original maximum likelihood based method by Wu (1985). © 2017 Grace Scientific Publishing, LLC.