Adaptive wavelet series estimation in separable nonparametric regression models

It is well-known that multivariate curve estimation suffers from the curse of dimensionality. However, reasonable estimators are possible, even in several dimensions, under appropriate restrictions on the complexity of the curve. In the present paper we explore how much appropriate wavelet estimators can exploit a typical restriction on the curve such as additivity. We first propose an adaptive and simultaneous estimation procedure for all additive components in additive regression models and discuss rate of convergence results and data-dependent truncation rules for wavelet series estimators. To speed up computation we then introduce a wavelet version of functional ANOVA algorithm for additive regression models and propose a regularization algorithm which guarantees an adaptive solution to the multivariate estimation problem. Some simulations indicate that wavelets methods complement nicely the existing methodology for nonparametric multivariate curve estimation.     

Shaping the digital transformation of the retail banking industry. Empirical evidence from Italy

Although numerous studies have investigated the determinants of users’ acceptance of online channels, little attention has been paid to the continuous usage of a direct bank. To address this research gap, we analysed data collected via semi-structured interviews and a survey questionnaire distributed in 2017 to a sample of Italian bank customers. Responses were evaluated using a different statistical methodology based on the Shapley Value regression analysis. In brief, user-friendliness and economic advantages appear to be more decisive at an early stage of adoption. Moreover, structural assurance mechanisms (e.g. clarifying security policies and guarantees) have a robust impact on keeping customers online and loyal to electronic channels. Surprisingly, accessibility and compatibility do not seem to be determinant factors.     

A comparison between VAR processes jointly modeling GDP and Unemployment rate in France and Germany

Statistical Methods & Applications - Investigating the relationship between Gross Domestic Product and unemployment is one of the most important challenges in macroeconomics. In this paper, we...