History of words II - types of historical developments

The development of the frequencies of Italian words was observed on data from a corpus including the end-of-year speeches of the 10 Presidents of the Italian Republic (1949-2012). The data used for this study were organised in two ways: For each word (lemma-types), the frequencies were collected in (1) 10 subcorpora (one for each president) and in (2) 64 subcorpora (one for each year within the period, i.e. one for each presidential address). The Piotrowski-Altmann Law, which was developed and used so far as a model also of the diffusion of new elements in a linguistic population, was considered as an appropriate model of the frequency dynamics over time. Fitting the corresponding function to the data sets yielded very good results in most cases after smoothing the data by calculating moving averages. The words could be ascribed to several categories of dynamics and the parameters of the Piotrowski- -Altmann Law proved a good way to cluster words portraying a similar temporal evolution.