Factorial trial found mixed evidence of effects of pre-notification and pleading on response to Web-based survey

To evaluate the effectiveness of pre-notification and pleading invitations in Web surveys by embedding a randomized controlled trial (RCT) in a Web-based survey.

E-mail addresses of 569 authors of published maternal health research were randomized in a 2×2 factorial trial of a pre-notification vs. no pre-notification e-mail and a pleading vs. a non-pleading invitation e-mail. The primary outcome was completed response rate, and the secondary outcome was submitted response rate (which included complete and partial responses).

Pleading invitations resulted in 5.0% more completed questionnaires, although this difference did not reach statistical significance [odds ratio (OR) 1.23; 95% confidence interval (CI): 0.86, 1.74; P=0.25]. Pre-notification did not increase the completion rate (OR 1.04; 95% CI 0.73, 1.48; P=0.83). Response was higher among authors who had published in 2006 or later (OR 2.07; 95% CI: 1.43, 2.98; P=0.001). There was some evidence that pre-notification was more effective in increasing submissions from authors with recent publications (P=0.04).

The use of a "pleading" tone to e-mail invitations may increase response to a Web-based survey. Authors of recently published research are more likely to respond to a Web-based survey.