This book includes a wide selection of papers presented at the 50th Scientific Meeting of the Italian Statistical Society (SIS2021), held virtually on 21-125 June 2021. It covers a wide variety of subjects ranging from methodological and theoretical contributions to applied works and case studies, giving an excellent overview of the interests of the Italian statisticians and their international collaborations. Intended for researchers interested in theoretical and empirical issues, this volume provides interesting starting points for further research.

A. Cutillo, M. Mazziotta, A. Pareto, A Composite Index of Economic Well-being for the European Union Countries.- Fulvio De Santis and S. Gubbiotti, Fulvio De Santis and S. Gubbiotti, A dynamic power prior for Bayesian non-inferiority trials.- Cinzia Di Nuzzo and S. Ingrassia, A graphical approach for the selection of the number of clusters in the spectral clustering algorithm.- M. Cefis and M. Carpita, A Higher-Order PLS-SEM approach to evaluate football players' performance.- Simone Del Sarto and P. Coppola and M. Troìa, A latent Markov approach for clustering contracting authorities over time using public procurement red flags.- I. Primerano, F. Santelli and C. Usala, A multiplex network approach for analyzing university students' mobility flows.- A. Briglia, M. Mucciardi and G. Pirrotta, A statistical model for predicting child language acquisition: unfolding qualitative grammatical development by using logistic regression model.- Fulvio Di Stefano and M. Gasparini, AdaptiveCOVID-19 screening of a subpopulation.- D. Barro, M. Corazza and M. Nardon, Alternative probability weighting functions in behavioral portfolio selection.- C. Scricciolo, Bayesian Quantile Estimation in Deconvolution.- M. Templ, Can the Compositional Nature of Compositional Data be Ignored by using Deep Learning Approaches?.- M. Pratesi, Citizen Data and Citizen Science: a challenge for Official Statistics.- M. Flora and R. Renò, Detecting states of distress in financial markets: the case of the Italian sovereign debt.- Forecasting combination of hierarchical time series: a novel method with an application to CoVid-19.- Raffaele Mattera and Germana Scepi, Frequency domain clustering: an application to time series with time-varying parameters.- Raffaele Grotti, Heterogeneous Income Dynamics.- Carlo Cavicchia, Pasquale Sarnacchiaro and Paolo Montuori, How much do Knowledge about and Attitude toward mobile phone use affect Behavior while driving? An empirical study using a Structural Equation Model.- Isabella Morlini, Impact of emergency online classes on students' motivation and engagement in University during the Covid-19 pandemic: A study case.- Federico Benassi, Annalisa Busetta*, Gerardo Gallo, Manuela Stranges, Local heterogeneities in population growth and decline. A spatial analysis of Italian municipalities.- Elias Fekhari, Bertrand Iooss, Joseph Muré, Luc Pronzato, and Maria-João Rendas, Model predictivity assessment: incremental test-set selection and accuracy evaluation.- Antonio Naimoli, Giuseppe Storti, Multiple measures Realized GARCH models.- Venera Tomaselli, Giulio Giacomo Cantone, and Vincenzo Miracula, Multiversal Methods in Observational Studies: The Case of COVID-19.- Fiorenzo Ambrosino, Giuseppe Giannini, Antonio Lepore, Biagio Palumbo, Gianluca Sposito.- Neural network for the statistical process control of HVAC systems in passenger rail vehicles.- Salvatore D. Tomarchio, Antonio Punzo and Luca Bagnato, On the use of the matrix-variate tail-inflated normal distribution for parsimonious mixture modeling.- Tiziana Tuoto, Davide Di Cecco and Andrea Tancredi, Population size estimation by repeated identifications of units. A Bayesian semi-parametric mixture model approach.- Ivan Sciascia, Andrea Crosino, Gennaro Carotenuto, Andrea Genre, Spatial interdependence of mycorrhizal nuclear size in confocal microscopy.- Federica Piersimoni and Francesco Pantalone and Roberto Benedetti, Spatially balanced indirect sampling to estimate the coverage of the agricultural census.- Michele Costa, The assessment of environmental and income inequalities.- Righi A., Catanese E., Valentino L., Zardetto D., The Italian Social Mood on Economy Index during the Covid-19 Crisis.- Maria Maddalena Barbieri, Francesca Bassi, Antonio Irpino, Rosanna Verde, The rating of journals and the research outcomes in Statistical Sciences in Italian Universities.- Mauro Bruno, Francesca Inglese, Giuseppina Ruocco, Trusted Smart Surveys: architectural and methodological challenges related to new data sources.- Elena Grimaccia, Alessia Naccarato, Gerardo Gallo, Web surveys: profiles of respondents to the Italian Population Census.