||The common understanding for ‘Productivity’ is quite straightforward: Its value increases if a company (or an economic, or a whole country) either produce more of some goods or services with the same resources (personnel and the rest of productive factors), or produce the same quantities of good and services with less of some of the resources; or a given mix of both types of moves, including trade-offs between favourable and unfavourable moves. Actually, data on productivity figures at an industry or country level have last years become one familiar component in the media news and in socio-political debate. Do those data on productivity (usually referred to labour productivity) talk us actually of productivity in the above sense? Surprisingly the answer is: not actually; even though those data are presented as out-of-discussion, since the acknowledged source for them are some official statistics institution, national or international, as Eurostat –for the EU countries-, OECD, BLS (US), . . etc. Then, what do actually mean those ‘productivity indexes’ for such and such country? How are they in fact calculated by the specialised agencies (first the nationals ones, then the Eurostat, OECD, etc. )? The present notes, written for non-professionals, try to answer such questions.