The book on the tertiary sector belongs to the studies defining a quantitative research on the structure of tertiary activities in Italy, developed by the Planning Studies Centre in 1977, on behalf of the SVIMEZ (a corporation devoted to the Development of the “Mezzogiorno”, the Southern regions of Italy).
The book serves as a propaedeutic reflection on the methodological organisation of the research. The conclusions of the book concerning “new methods of analysing the tertiary sector” have constituted a rationale of the above-mentioned research. In fact, on the occasion of this research, the inopportunity of a – largely obsolete – “commodities” definition of the tertiary sector has been reasserted; however, one definition exists based on three criteria by means of which the logical mechanisms of evaluating a productive structure of tertiary activities could be filtered:

- productivity (or “internal” productive efficiency)
- individual usefulness (or external individual efficiency)
- and, finally, social usefulness (or external social efficiency).

If then the tertiary sector is to be valued, in its dimension and its efficiency on the basis of the above-mentioned criteria or gauges, there follows only that the existence of a tertiary sector within the limits of individual and social convenience will depend on the use of a system of indicators, without which any reading of the situation of the tertiary becomes mute and unintelligible. It is then only on said measurements that the decision depends as to whether the situation in which they meet is positive or negative (also merely from the point of view of business services), whether to be hindered or favoured etc. And it is only from the measurements, applied on the basis of these criteria, that – situation-by-situation – the opportunity of a policy of encouragement or discouragement of the development of tertiary activities can be derived.