An initial Request for Proposal (RFP) is required before proceeding with the survey. This RFP includes the list of 36+ experts, stratified in 9 EFCs together with the justification for the selection of each expert plus their professional background, contact details and request for permission to interview date.

The RPF data is checked by the NES coordinator, who either accepts the files or provides feedback for corrections, or rejects them if they do not meet the GEM conditions.

National Teams are required to use the online platform created for each team, if not to conduct the interviews then at least to introduce the collected data. The online platform auto-checks the quality since if the experts do not complete all the required fields, the interview is rejected. The platform automatically generates an SPSS file that is sent to the National Team for review.

The NES data is also tested for the reliability of the blocks. These tests were designed under theoretically justified constructs and have proved to be stable since 1999.