Supplementing online surveys with a mailed option to reduce bias and improve response rate: the National Dental Practice-Based Research Network

J Public Health Dent. 2014 Fall;74(4):276-82. doi: 10.1111/jphd.12054. Epub 2014 Apr 7.


Objective: Dentists in the National Dental Practice-Based Research Network are offered online and mail options for most questionnaire studies. We sought to quantify differences a) in characteristics of dentists who completed a questionnaire online as compared with those who completed a mail option offered to online nonresponders and b) in prevalence estimates for certain practice characteristics.

Methods: Invitation letters to participants provided an identification number and log-in code with which to complete the online survey. Nonrespondents received a reminder letter after the fourth week, and after an additional 4-week period, a final reminder was sent, along with a paper questionnaire version, allowing completion online or by paper.

Results: Of 632 US dentists who completed the survey, 84 (13 percent) used the paper version. Completion by paper was more common among males, older dentists, and those in general practice (P<0.05). The proportions of dentists who used electronic dental records, who consistently used a rubber dam when performing root canals, and who either worked with or employed expanded-function auxiliaries were lower among dentists who completed the survey using the paper-mail version than among those who completed it online; these differences remained significant in models adjusted for gender, age, and practice type.

Conclusion: Even in an era of increasingly electronic communication by dentists, not including a paper option when conducting surveys can result in overestimation of the prevalence of key dental practice characteristics.

Keywords: bias; dental care; health surveys; online; questionnaires.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Data Collection*
  • Female
  • Humans
  • Internet
  • Male
  • Postal Service
  • Practice Management, Dental / organization & administration*
  • Practice Patterns, Dentists'
  • United States