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Effects of attrition in the Norwegian Survey on statistics on income and living conditions. Marit Wilhelmsen Statistics Norway Q2010 - European Conference on Quality in Official Statistics, Helsinki, Finland 4-6 May 2010. Effects of attrition in the EU-slic.
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Effects of attrition in the Norwegian Survey on statistics on income and living conditions Marit Wilhelmsen Statistics Norway Q2010 - European Conference on Quality in Official Statistics, Helsinki, Finland 4-6 May 2010
Effects of attrition in the EU-slic • The response rate has been declining over recent years. • What are the known background characteristics of the people that participate? • How severe is the extent of attrition in the EU-silc? • Is attrition influenced by the same characteristics as non response? • Do attrition lead to increased survey bias, introduced in the first wave?
Background • The sample units are persons aged 16 or more registered in the central population register (inhabitants). • A rotational design was chosen to ensure both cross-sectional and longitudinal data. This design rotate a part of the sample form one year to the next retaining the other part unchanged. • The sample units are asked to participate eight years in a row. Each year 1/8 of the sample will be replaced. • We look the group drawn in 2003 and follow it until 2008. (n = 1066) • We follow the respondent from the first wave T1 in 2003. (n= 731)
Attrition in the Eu-silcResponse rate for participants in T1 (2003) in 2004 - 2008
Logistic regression. Interviewed in 2003. Dependent variable: Interview in 2008
Concluding remarks • To some extent attrition follows the same pattern as non response in the first wave. Education and young age matter if you participate or not • Difficult to conclude if attrition leads to increased survey bias that where introduced in the first wave. • Probably there are other unknown factors that decide if you participate or not, that might not be as selective • Recruitment in the first wave is the most important factor for further recruitment in the survey.