Non-response
Non-response is a form of the non-observation present in most surveys, which means failure to obtain a measurement on one or more study Variables for one or more elements selected for the survey. The term encompasses various reasons for non-observation, such as: Impossible to contact, not at home, unable to answer, incapacity, hardcore refusal, inaccessible, or unreturned questionnaire. In the first two cases, contact with the selected elements has yet to be established. There are two broad types of Non-response: Unit non-response, which means that a sampled unit that is contacted may fail to respond (Total non-response), and Item non-response, which means that the unit may respond to the questionnaire incompletely (Partial non-response). Non-response leads to an increase in variance because of a reduction in the actual size of the sample. If the non-respondents have characteristics of interest that differ from those of the respondents, Non-response can produce a Bias.
Furthermore, there is a risk of significantly underestimating the Sampling error if imputed data are treated as though they were observed data. For Administrative data, Unit non-response has to be seen in connection with the Under-coverage of the Administrative data source. Item non-response refers to missing information for Administrative variables. The importance of Non-response for the quality of Frames is treated in ESSnet KOMUSO-SGA3, WP2.
In a more general context, see also: Statistics Canada: “Quality Guidelines”; 5th edition (2009)[CROS - European Commission]. Non-response leads to an increase in variance due to a reduction in the actual size of the sample and the recourse to imputation. This produces a bias if the non-respondents have characteristics of interest that differ from those of the respondents.
Furthermore, there is a risk of significantly underestimating the sampling error if imputed data are treated as though they have observed data[OECD Glossary of Statistical Terms].
Non-response. CROS - European Commission. Retrieved from: https://ec.europa.eu/eurostat/cros/content/non-response_en
Non-response Definition.OECD Glossary of Statistical Terms. Retrieved from: https://stats.oecd.org/glossary/detail.asp?ID=3764