Advance letters as a way of reducing non-response in a National Health Telephone Survey: Differences between listed and unlisted numbers

Elena von der Lippe, Patrick Schmich, Cornelia Lange


The paper reports a methodological study based on the German Health Update Survey 2009. The study generated telephone numbers randomly and determined the listing status of the selected numbers. The set of listed numbers was randomly split: one half received advance letters, the other half did not. Differences in response rates and demographic characteristics are analyzed in detail.


CATI; Nonresponse

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