The industrial production index (IPI) is a statistical instrument that measures variations in the quantities produced by industry. If we refer to the traditional classification of economic activities in three sectors, the IPI concerns the so-called secondary sector: factories, construction sites, mines and quarries. The products that are monitored are to be found at all the levels in the manufacturing processes. These are Laspeyres indices (constant weighting) calculated by INSEE on the basis of the branch surveys by the statistics departments of ministries (Sessi, Scees, Energy Observatory), unions and professional organisations. These indices are monthly and are corrected for seasonal variations and for working days.
We usually speak of the industrial output index (in the singular) when we are interested only in the macro-economic indicator relating to the whole of national manufacturing industry, and of production output indices (in the plural) when we are speaking of the full system describing both the evolution in output of all the broad industrial branches, sub-branches and detailed families of industrial products.