In the first quarter of 2009, additional questions were introduced to the electronic questionnaire for the Economically Active Population Survey in order to better identify the variable professional status.

This produced a variation in the distribution of employed persons among the different professional status categories, increasing the number of wage earners, and reducing by that same number of self-employed workers. Once an adequate amount of time had elapsed using the additional questions from the questionnaire, which identifies professional status, it was possible to analyse the change in detail, and compile a series linking providing uniform estimates for this variable. The document New questions regarding professional status 2009. 2005-2008 Professional status series linking collects the compilation methodology for series; likewise is provided a set of tables with the recalculated data for the 2005-2008 Series of employed persons by professional status.