I devoted particular attention to the study of non-linear multilevel models, particularly to models with ordered categorical response variables for which I studied the comparison among different estimation methods for the regression parameters (the Gauss-Hermite numerical integration method, MQL and PQL methods, and methods based on MCMC simulation). From the application point of view, I focused on two-level models to assess satisfaction and its determinants in the social services sector.
Another field of study of interest is that relating to distances between ranks, in particular Cayley, Kendall and Hamming distances. The focus, in this area, has been identified in position and dispersion measurements for unimodal and multimodal frequency distributions.
In the biomedical field, great attention has been devoted to:
-comparison of classification model performance and development of an assessment tool by appropriate modification of the weighted Cronbach's Alpha index.
- description of multidimensional categorical data and application of non-linear mixed-effects models to the evaluation of alternative treatments
-use of permutation models for the treatment of longitudinal data.
I am also interested in the detection and evaluation of individual perceptions by means of appropriate questions and survey scales, in order to properly evaluate latent variable
