nonrespondent

A nonrespondent is a term used to describe an individual or entity that does not provide data in response to a survey, census, questionnaire, interview, or other data collection instrument. In research contexts, nonrespondents may be unreachable or may choose not to participate.

Unit nonresponse occurs when no data are obtained from an eligible unit; item nonresponse refers to missing answers to particular questions. Nonresponse can lead to nonresponse bias if the characteristics of nonrespondents differ from those of respondents, potentially affecting estimates of population parameters.

Researchers use several measures to assess and address nonresponse. The response rate, or the proportion of eligible units that participate, is a basic indicator. Bias is often evaluated by comparing early versus late respondents, conducting follow-up studies, or using auxiliary data. Mitigation strategies include multiple contact attempts, incentives, reducing respondent burden, offering alternative modes (online, phone, mail), and applying statistical adjustments such as weighting or imputation to reduce the impact of missing data.

In clinical research, nonrespondents may be patients who discontinue participation or fail to complete study procedures. In legal contexts, a nonrespondent can refer to a party that fails to respond to a subpoena or court order, though terminology varies across jurisdictions.

Overall, the concept of nonresponse encompasses instances where data are not provided, with implications for data quality, inference, and decision-making across disciplines.