Antonio Giusti

Cluster analysis of census data using the symbolic data approach

The aim of this paper is to investigate the economic specialization of the Italian local labor systems (sets of contiguous municipalities with a high degree of self-containment of daily commuter travel) by using the Symbolic Data approach, on the basis of data derived from the Census of Industrial and Service Activities. Specifically, the economic structure of a local labor system (LLS) is described by an interval-type variable, a special symbolic data type that allows for the fact that all municipalities within the same LLS do not have the same economic structure.

Disclosure control on multi-way tables by means of the shuttle algorithm: extensions and experiments

In this paper we re-examine our algorithm for calculating the lower and upper bounds of an array given the complete set of its marginals, proposing some extensions. The algorithm has some interesting properties that can be useful in various fields of application, such as statistical disclosure control of count tables. These properties involve both theoretical and computational issues: in particular, the algorithm has relevant links with probabilistic and statistical aspects (e.g. Frechet and Bonferroni bounds) and is particularly easy to implement, has a low storage requirement and is very fast.

On the Assessment of Geographical Survey Units using Constrained Classification

Surveys of spatially distributed phenomena are often conducted using geographical areas as strata. If CATI (computer assisted telephone interviewing) methodology is used to contact the units, it is possible to choose between two different methods of selecting the units to be interviewed: either from a full list of the population units or a selection based on RDD (random digit dialling) technique. On this last case it seems natural to telephone exchange areas as strata. This could be a very interesting solution from many point of views. The aim of this paper is to find a methodology to asses the opportunity of using such a pre-defined geographical stratification in comparison of the usual clustering methods, based on a set of auxiliary variables correlated with the phenomena under study, to define the strata. The choice will depend on the use of some measure of similarity and/or the evaluation of the homogeneity in the strata for the specific phenomenon to be analysed (in our application the evaluation of the loss of homogeneity is verified with respect to a hypothetical set of variables under study).