Key points are not available for this paper at this time.
A telephone presurvey is used in conjunction with mail and Internet follow-up surveys to assess self-selection and item nonresponse bias. Findings suggest that self-selection is present, but item nonresponse bias is limited. The Internet version exhibited no item nonresponse bias.
Hudson et al. (Mon,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: