In statistics, '''non-sampling error''' is a catch-all term for the deviations of estimates from their true values that are not a function of the sample chosen, including various systematic errors and random errors that are not due to sampling.<ref name=Dodge>Dodge, Y. (2003) ''The Oxford Dictionary of Statistical Terms'', OUP. {{ISBN|0-19-920613-9}}</ref> Non-sampling errors are much harder to quantify than sampling errors.<ref name="Scheuren">Fritz Scheuren (2005). "What is a Margin of Error?", Chapter 10, in "[http://www.amstat.org/sections/srms/pamphlet.pdf What is a Survey?] {{Webarchive|url=https://web.archive.org/web/20130312125540/http://www.amstat.org/sections/srms/pamphlet.pdf |date=2013-03-12 }}", American Statistical Association, Washington, D.C. Accessed 2008-01-08.</ref>
Non-sampling errors in survey estimates can arise from:<ref name=QFR/>
* Coverage errors, such as failure to accurately represent all population units in the sample, or the inability to obtain information about all sample cases; * Response errors by respondents due for example to definitional differences, misunderstandings, or deliberate misreporting; * Mistakes in recording the data or coding it to standard classifications; * Pseudo-opinions given by respondents when they have no opinion, but do not wish to say so * Other errors of collection, nonresponse, processing, or imputation of values for missing or inconsistent data.<ref name=QFR>U.S. Census Bureau. March 2012. Introduction. [http://www2.census.gov/econ/qfr/pubs/qfr11q4.pdf ''Quarterly Financial Report for Manufacturing, Mining, Trade, and Selected Service Industries''. Fourth Quarter 2011.] p. xxi</ref>
An excellent discussion of issues pertaining to non-sampling error can be found in several sources such as Kalton (1983)<ref>Kalton, Graham. Introduction to survey sampling. Vol. 35. Sage, 1983.</ref> and Salant and Dillman (1995),<ref>Salant, Priscilla, and Don A. Dillman. "How to Conduct your own Survey: Leading professional give you proven techniques for getting reliable results." (1995).</ref>
== See also == * Errors and residuals in statistics * Sampling error
== References == {{Reflist}}
Category:Survey methodology Category:Errors and residuals Category:Auditing terms
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