Random individual samples within households or how inadequate methodologies lead to a waste of time and money

Date of publication: September 1, 1994

Company: NIPO

Author: Theo Hess


This paper demonstrates that those random procedures for selecting individuals in households will lead to enormous shortcomings in the representativeness of the individual sample while the agencies will need a second or third wave to obtain a minimum of representativeness. This is a costly sampling procedure which can easily be avoided. The basic assumption underlying the study presented in the paper is that nowadays one-person households and two-person households are in the majority in most European countries. This means that individuals living in such households have a far greater chance of being drawn in random individual samples than persons living in three-or-more person households. As persons living in smaller households have different socio-economic characteristics from persons living in larger households, random samples of individuals lead to wrong results - not only in terms of socio-economic characteristics, but also in the results of practically every market research study based on individuals. The study described was performed in NIPO's Telepanel where a questionnaire was used by applying different selection procedures. The paper describes the results of a few questions about political preference by applying the various methods. Finally an extremely practical solution will be discussed. This selection method - whose value is borne out by the results - is to select within the household: in a panel situation: youngest person (from a certain age) in a cross-section situation: youngest male and if not present youngest female (from a certain age).

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