Table 3:

Strategies that enhance or reduce the response rate to electronic questionnaires22

StrategyNo. of studiesNo. of participantsOdds ratio (95% CI)Heterogeneity*
I2 value, %p value
Enhances response rate
Nonmonetary incentive617 4931.72 (1.09–2.72)96< 0.001
Shorter questionnaire27 5891.73 (1.40–2.13)680.08
Statement that others had responded18 5861.52 1.36–1.70)NANA
More interesting topic12 1761.85 (1.52–2.26)NANA
Lottery with immediate notification of results12 2331.37 (1.13–1.65)NANA
Offer of survey results12 3321.36 (1.15–1.61)NANA
Use of a white background16 0901.31 (1.10–1.56)NANA
Personalized questionnaire1248 9101.24 (1.17–1.32)410.07
Simple header15 0751.23 (1.03–1.48)NANA
Textual representation of response categories15 4131.19 (1.05–1.36)NANA
Deadline given18 5861.18 (1.03–1.34)NANA
Picture included in email27203.05 (1.84–5.06)190.3
Reduces response rate
Survey mentioned in email subject line23 8450.81 (0.67–0.97)00.3
Male signature in email message27200.55 (0.38–0.80)00.96
  • Note: CI = confidence interval, NA = not applicable.

  • * See Table 2 for explanation of heterogeneity.