Pesi e Metriche nell'Analisi dei Dati Testuali

The paper goes through some tools considered nowadays classical in Text Mining procedures and software. We are speaking of Latent Semantic Indexing for dimensionality reduction, and the wide literature devoted to the problem of how to weight the word importance, and how to measure similarities between words and between words and queries. Visualisation is strongly affected by these choices. Here we compare some alternatives from a statistical viewpoint. A corpus consisting of six years of the Italian edition of Le Monde Diplomatique is analysed in order to show the effects of the different weighting systems together with the potentiality of Textual Data Analysis in summarising and representing newspaper information