34: Item Nonresponse

Nonresponse in travel surveys is an issue that has received considerable attention in the past two decades. It is of particular concern in the United States, where response rates are declining and resistance to surveys is growing. Such resistance usually results in increased unit nonresponse but it can impact item nonresponse as well. Antagonistic or reluctant respondents are more likely to omit, misread, or falsify information. In addition, they are more likely to be sensitive to personal questions in the survey and be more suspicious that information provided in the survey will be used against them in the future.

There is a clear need to know the extent and understand the impact of item nonresponse in travel surveys. This chapter sets out to clarify the concept of item nonresponse, identify its impact on survey quality, review methods used to treat it, suggest standards that would facilitate dealing with item nonresponse, and recommend research that should be conducted to further understand and treat item nonresponse.