The harmonization process takes place when all the national and regional files have been delivered and checked. The following process is followed:

• Creation of the global NES SPSS file that includes the individual responses of the experts from all participating nations

• Calculation of the reliability measures on the blocks that form the closed part of the questionnaire and evaluation of the global reliability of the individual level data

• Creation of the report on the reliability of the national NES individual level data

• Calculation of the summary variables as the output of a Principal Component analysis

• Creation of the harmonized individual SPSS files that include the scores of the summary variables for each nation

• Creation of the global aggregated comparative file of the nations (the "Global National Level" file)

• Creation of the global NES SPSS file that includes the individual responses of the experts of all participating regions within each nation that developed a regional project (the "Global Individual Level" file)

• Calculation of the reliability measures on the blocks that form the closed part of the questionnaire and evaluation of the global reliability of the data for each group of regions within a country

• Creation of the report on the reliability of the regional NES data within each country that developed a regional project

• Calculation of the summary variables as the output of a Principal Component analysis

• Creation of the harmonized individual SPSS files that include the scores of the summary variables for each region

• Creation of the global aggregated comparative SPSS file of the regions of each nations that developed a regional project

• Creation of the global aggregated comparative SPSS file of the nations plus the participating regions

• Creation of the global aggregated comparative file of all levels, which includes the GEM global averages, national and regional averages, world regions, countries’ economic development levels and other groups of interest
  

All these operations are based upon rigorous and controlled SPSS syntax files adapted for each edition and stored for each year by the GEM Data Team. To assist in the understanding of the products derived from the harmonization process, a description of the different types of files is included below:

• A NES Individual SPSS file includes the individual responses of all the participating experts.

• A reliability report includes the Cronbach’s Alphas calculated for each block of questions that is later summarized by a Principal Components Analysis. In this report, the numbers of valid cases for each item and other details are also included.

• An NES aggregated file is a comparative file in which each row represents a country (or a region), and provides medians, means, standard deviations for each item of the original closed data for each nation (or region), plus the means and standard errors of the summary variables and the percent of multiple responses of the opened questions. These last, are coded thanks to a list of topics that facilitates the identification of the issue highlighted by the original textual response.
  

The harmonization process ends when all the described files have been created, and after the last quality control, they are delivered to participating teams and to the general public after the grace period.