ABSTRACT
Before outlining sampling techniques it is worth introducing a few technical terms. A census is obtained by collecting information about every member of a group; that is, the population. In sampling, population has a technical meaning and should not be confused with the population of a country or a region. A population is the set of units that the sample is meant to represent. The
units that make up the population will depend on the units of analysis (see Chapter 3). In national surveys the population is usually defined as all adults (18+) who are non-institutionalised (i.e. live in households). For another study the population might be all employed people or all families with children under five years old.
