Sample and recruitment
The LISS panel is specifically intended for scientific research. For this reason, the quality and the coverage of the sample is of prime concern. To establish the LISS panel, a traditional random sample was drawn from the population registers, in collaboration with Statistics Netherlands (Centraal Bureau voor de Statistiek, CBS). This sample includes people without an Internet connection.
Secondly, all people in the sample were approached in traditional ways (by letter, followed by telephone call and/or house visit) with an invitation to participate in the panel. Persons not included in the original sample cannot participate, so there can be no self-selection.
People without a prior computer or Internet connection are also able to participate in the LISS panel. These participants are loaned equipment to provide access to the Internet via a broadband connection.
A full description of the original sample, the recruitment process and the recruitment response is given here.
The recruitment of a refreshment sample was carried out between June and December 2009. In cooperation with Statistics Netherlands, we have drawn a stratified sample intended to improve the representativeness of the panel by oversampling the difficult to reach groups which had a below-average response in the main recruitment. The refreshment sample in 2009 was stratified on three variables: 1) household type, 2) age, 3) ethnicity.
Another refreshment sample for the LISS panel was recruited between October 2011 and May 2012. This sample was randomly drawn from the population register by Statistics Netherlands, in the same way as the original sample of 2007.
In 2010, a special sample of immigrants was drawn by Statistics Netherlands from the population register, stratified by country of origin. This resulted in the Immigrant panel. In addition to the LISS refreshment sample in 2011, a small stratified sample was drawn and recruited at the same time to correct for the initial bias in the Immigrant panel with regards to ethnicity.