Effective April 1, 2017, the methodology changes:  See Services Production index, Turnover index in services, Sales volume index in trade and Turnover index in trade.

From 2016 the calculation of the turnover indices is realised from the exhaustivity of the monthly declarations of the fiscal source. This new methodology of calculation of the indices was implemented to take better into account the demography of companies and so it shows more precisely the economic reality. Indeed the indices of turnover of one year N previously calculated did not take into account new business start-ups, terminations, entrances into the statistic sphere, exits of the statistic sphere, and changes of sector which happened during the year N, the sample being done the 31/12 of the year N-1.
Within the framework of a project for a renovation of the turnovers indices, solutions were implemented to correct this bias and to produce turnover indices with better quality. On one hand, annual samples will not be used anymore and all of the monthly declarations of VAT will be exploited, the progress of the computing allowing to handle very big volumes of data nowadays; on the other hand,  the statistical directory Sirus will be used instead of the administrative directory Siren, so as to benefit from a provision much faster and automated of the most recent demographic events companies have been affected.
Turnover indices in retail trade and personal services are monthly indices of value in current euros excluding VAT; sales indices in volume are also calculated in retail trade and personal services.
These indices are calculated in relation to a reference of 100 in 2010 (the indices had a mean of 100 in 2010). They are calculated as Laspeyres indices, with constant weightings over time of the most discriminating indices, and are rebased every five years.
Sales volume and turnover indices in retail trade and personal services are adjusted for seasonal variations (SDA) and for calendar effects (adjustment for working days – WDA).