The artificial neural network (ANN) test of Lee et al. (Journal of Econometrics 56, 269–290, 1993) uses the ability of the ANN activation functions in the hidden layer to detect neglected functional misspecification. As the estimation of the ANN model is often quite difficult, LWG suggested activate the ANN hidden units based on randomly drawn activation parameters. To be robust to the random a...

In view of its ongoing importance for a variety of practical applications, feature selection via `1-regularization methods like the lasso has been subject to extensive theoretical as well empirical investigations. Despite its popularity, mere `1-regularization has been criticized for being inadequate or ineffective, notably in situations in which additional structural knowledge about the predic...

Electrical capacitance tomography (ECT) attempts to image the permittivity distribution of an object by measuring the electrical capacitance between sets of electrodes placed around its periphery. Image reconstruction in ECT is a nonlinear ill-posed inverse problem, and regularization methods are needed to stabilize this inverse problem. The reconstruction of complex shapes (sharp edges) and ab...