Table 1 presents the population - versus sample distribution per age group in the Meuse-Rhine Euroregion. Participation in round 1 In total, 26,925 citizens in the EMR received an invitation to participate in the study. Three hundred twenty invitations never arrived at their destination: 250 in Germany, 46 in Belgium and 24 in the Netherlands. The opt-out rate in South Limburg (NL) was 33.7% (2,358 opt-outs) in the initial sample and 38.2% (1,638 opt-outs) in the reserve sample.
