FONTANA , Roberto

Given an orthogonal array we analyze the aberrations of the sub-fractions which are obtained by the deletion of some of its points. We provide formulae to compute the Generalized Word-Length Pattern of any sub-fraction. In the case of the deletion of one single point, we provide a simple methodology to find which the best sub-fractions are...

Generalized Word Length Pattern (GWLP) is an important and widely-used tool for comparing fractional factorial designs. We consider qualitative factors, and we code their levels using the roots of the unity. We write the GWLP of a fraction F using the polynomial indicator function, whose coefficients encode many properties of the fraction. We...

The use of the Gini index in Design of Experiments is unexplored. We present here some connections between the aberration of a fractional factorial design and the Gini concentration index of the fraction terms. In fact, both the aberration and the Gini index depend on geometrical properties of the fraction. The main tool in our theory is the...

This special issue collects a selection of papers that were originally presented at the workshop on 'Demand, Product Characteristics and Innovation' organized at the Friedrich Schiller University in Jena in October 2007. The workshop was funded by the DIME (Dynamics of Innovation and Markets) Network of Excellence of the European Commission....

In this work we focus on saturated D-optimal designs. Using recent results, we identify D-optimal designs with the solutions of an optimization problem with linear constraints. We introduce new objective functions based on the geometric structure of the design and we compare them with the classical D-efficiency criterion. We perform a...