Documentation of statistics: Business Services in the Sector for Market Research and Public Opinion Polling
All enterprises within the population are required to submit to the statistics and the submitted turnover is subject to adjustments against the turnover from Accounts Statistics for Non-Agricultural private sector, which consists of a large sample, administrative sources and XBRL reports from the Danish Business Authority.
https://www.dst.dk/en/Statistik/dokumentation/documentationofstatistics/business-services-in-the-sector-for-market-research-and-public-opinion-polling
Documentation of statistics