One key objective of a survey project is to be able to generalise from the sample studied to the population of interest in the most error-free way possible. This is significantly influenced by the sampling method. The contributions to this section address the theoretical issues of sampling and their implementation in different survey modes and intercultural surveys.
If necessary, the quality of a sample can be improved by means of suitable weighting procedures. Moreover, different procedures can be implemented to minimise unit nonresponse and the associated sampling bias. The contribution on nonresponse bias provides an overview of unit-nonresponse and methods that can help to control it. Specific methods, such as incentives and interviewer training, which have been discussed as possible ways of increasing participation in surveys, are dealt with in further contributions.