Università della Svizzera italiana

Estimation of generalized linear latent variable models

Huber, Philippe ; Ronchetti, Elvezio ; Victoria-Feser, Maria-Pia

In: Journal of the Royal Statistical Society: Series B (Statistical Methodology), 2004, vol. 66, no. 4, p. 893–908

Generalized Linear Latent Variable Models (GLLVM), as defined in Bartholomew and Knott (1999) enable modelling of relationships between manifest and latent variables. They extend structural equation modelling techniques, which are powerful tools in the social sciences. However, because of the complexity of the log-likelihood function of a GLLVM, an approximation such as numerical integration must...

Università della Svizzera italiana

Fréchet and robust statistics

Ronchetti, Elvezio

In: Journal de la Société Française de Statistique, 2006, vol. 147, no. 2, p. 73-75

Università della Svizzera italiana

General saddlepoint approximations of marginal densities and tail probabilities

Gatto, Riccardo ; Ronchetti, Elvezio ; della Svizzera italiana, Svizzera

In: Journal of the American statistical association, 1996, vol. 91, no. 434, p. 666-673

Saddlepoint approximations of marginal densities and tail probabilities of general nonlinear statistics are derived. They are based on the expansion of the statistic up to the second order. Their accuracy is shown in a variety of examples, including logit and probit models and rank estimators for regression.

Università della Svizzera italiana

Indirect robust estimation of the short-term interest rate process

Czellara, Veronika ; Karolyib, G. Andrew ; Ronchetti, Elvezio

In: Journal of Empirical Finance, 2007, vol. 14, no. 4, p. 546-563

We propose Indirect Robust Generalized Method of Moments (IRGMM), a simulationbased estimation methodology, to model short-term interest rate processes. The primary advantage of IRGMM relative to classical estimators of the continuous-time short-rate diffusion processes is that it corrects both the errors due to discretization and the errors due to model misspecification. We apply this approach...

Università della Svizzera italiana

Optimal conditionally unbiased bounded-influence inference in dynamic location and scale models

Mancini, Loriano ; Ronchetti, Elvezio ; Trojani, Fabio

In: Journal of the American Statistical Association, 2005, vol. 100, no. 470, p. 628-641

This paper studies the local robustness of estimators and tests for the conditional location and scale parameters in a strictly stationary time series model. We first derive optimal bounded-influence estimators for such settings under a conditionally Gaussian reference model. Based on these results, optimal bounded-influence versions of the classical likelihood-based tests for parametric...

Università della Svizzera italiana

Robust and accurate inference for generalized linear models

Lô, Serigne N. ; Ronchetti, Elvezio

In: Journal of multivariate analysis, 2009, vol. 100, no. 9, p. 2126-2136

In the framework of generalized linear models, the nonrobustness of classical estimators and tests for the parameters is a well known problem and alternative methods have been proposed in the literature. These methods are robust and can cope with deviations from the assumed distribution. However, they are based on ¯rst order asymptotic theory and their accuracy in moderate to small samples...

Università della Svizzera italiana

A robust approach for skewed and heavy-tailed outcomes in the analysis of health care expenditures

Cantoni, Eva ; Ronchetti, Elvezio

In: Journal of Health Economics, 2006, vol. 25, no. 2, p. 198-213

In this paper robust statistical procedures are presented for the analysis of skewed and heavy-tailed outcomes as they typically occur in health care data. The new estimators and test statistics are extensions of classical maximum likelihood techniques for generalized linear models. In contrast to their classical counterparts, the new robust techniques show lower variability and excellent...

Università della Svizzera italiana

Robust inference

Ronchetti, Elvezio

In: International encyclopedia of statistical science, 2011, p. 1240-1242

Università della Svizzera italiana

Robust inference for generalized linear models

Cantoni, Eva ; Ronchetti, Elvezio

In: Journal of the American Statistical Association, 2001, vol. 96, no. 455, p. 1022-1030

By starting from a natural class of robust estimators for generalized linear models based on the notion of quasi-likelihood, we de¯ne robust deviances that can be used for stepwise model selection as in the classical framework. We derive the asymptotic distribution of tests based on robust deviances and we investigate the stability of their asymptotic level under contamination. The binomial and...