The concept of prototype is one of the most popular ones in modern Linguistics, and can be applied to many phenomena consisting of a center and a periphery. But this advantage is a disadvantage too, since it is difficult to objectivize the criteria that would lead to a fuzzy categorization. The theory may then seem based on subjective, researcher-dependent criteria. In this work we claim for the need of a formalization of the theory and we suggest that it can be achieved by measuring a prototype with the help of statistical techniques.

The major problem with the measure of a concept lies in the fact that a qualitative concept should be quantified. Some of the more recent findings in Multivariate Statistics point towards the quantification of subjective concepts such as tastes and smells.

We claim that this theoretical framework can be successfully applied to cognitive linguistics and we exemplify it with the definition of the term connective. Trying to determine its scope, an inductive analysis has been performed in which eleven central and peripherical connectives have been analized, on a corpus of casual style Spanish conversations. Twenty one questions have been asked to any occurence of them.

After the analysis, the application of Multivariate Statistics lets the qualitative corpus to be quantified and a diagram can be drawn, in which central and peripherical connectives are measured as the output of the quantification process. The concepts of center and periphery can be seen now as the joint effort of linguistic subjective analysis and mathematical objective techniques.