Addressing nonresponse bias in postal surveys.

Postal surveys are sometimes thought of as a simple option for collecting data in community-based studies; however, nurse researchers must exercise care in appropriately addressing the issue of nonresponse. In particular, both the reporters and the users of such research should look beyond survey response rates when considering nonresponse bias. This article describes the benefits of using postal surveys in public health nursing research, while noting the various potential sources of survey error. Particular attention is directed to the implications of low survey response rates, including decreased power, increased standard error, and nonresponse bias. The belief that increasing response rates will necessarily reduce nonresponse bias is discussed, with an emphasis on the need to identify the reasons for nonresponse and to be judicious in the use of strategies to reduce nonresponse bias. Common response-enhancement strategies are identified, while noting the potential for these strategies to increase nonresponse bias. Assessment of the presence and magnitude of nonresponse bias is discussed, and techniques for postsurvey data adjustment are noted. The need to consider nonresponse bias in designing all phases of the study is highlighted, and is exemplified with a case study.