Rosalinda Allegro received her PhD from the University of Palermo and currently works as a statistician at the Istituto Zooprofilattico Sperimentale della Sicilia (Experimental Zooprophylactic Institute of Sicily) in Palermo. She has previously worked at the Department of Economic Science, Business, and Statistics at the University of Palermo and in public and private companies as a statistical consultant. Her work focuses mainly on Quantitative Social Research and Biostatistics and she is co-author of scientific papers in these fields. This book is one of the outcomes of her activity at the University of Palermo. Ornella Giambalvo is Full Professor in the Department of Economic Science, Business, and Statistics at the University of Palermo. Her work focuses mainly on social statistics, sampling surveys, the construction of statistical indicators, and studies on statistical education. She is referent for the University of Palermo in the AlmaLaurea interuniversity consortium, with responsibility for collecting survey data for the assessment units and the committees dealing with teaching activities and career guidance. She is a member of both the AlmaLaurea Scientific Committee and the CRUI (Italian Conference of Rectors) Scientific and Technical Committee for Soft Skills. This book is one of the outcomes of her activity on these scientific committees.