Reevaluating the need for concern regarding noncoverage bias in landline surveys

Objectives. We used recent data to reexamine whether the exclusion of adults from households with no telephone or only wireless phones may bias estimates derived from health-related telephone surveys. Methods. We calculated the difference between estimates for the full population of adults and estimates for adults with landline phones; data were from the 2007 National Health Interview Survey. Results. When data from landline telephone surveys were weighted to match demographic characteristics of the full population, bias was generally less than 2 percentage points (range=0.1-2.4). However, among young adults and lowincome adults, we found greater bias (range=1.7-5.9) for estimates of health insurance, smoking, binge drinking, influenza vaccination, and having a usual place for care. Conclusions. From 2004 to 2007, the potential for noncoverage bias increased. Bias can be reduced through weighting adjustments. Therefore, telephone surveys limited to landline households may still be appropriate for health surveys of all adults and for surveys of subpopulations regarding health status. However, for some behavioral risk factors and health care service use indicators, caution is warranted when using landline surveys to draw inferences about young or low-income adults.