- The Health Interview Survey has to result in a net sample of 10.000 participants.
- A stratified multistage, clustered sampling method is applied, in which the regional net samples are fixed (3.500 in the Flemish Region and in the Walloon Region and 3.000 in the Brussels’ Region. The net sample in the Walloon region should comprise 300 interviews in the German Community.
- The National Population Register is used as a sampling frame.
- In every region, a limited number of cities and municipalities are selected. In every selected city or municipality, a limited number of households are selected. In every selected household a maximum of 4 members will be selected for interview.
- The results are weighted to reflect the composition of the population.