Print format and sender recognition were related to survey completion rate

To assess whether print format (single-sided vs. double) and sender recognition (known vs. unknown) affect response and completion rates among physician survey respondents.

Postal survey of 399 members of the Canadian Association of Emergency Physicians; 2 x 2 factorial design.

Response rate was 69.4%. Single-sided printing yielded 7.4% (odds ratio OR = 1.41; 95% confidence interval CI = 0.90-2.20; P = 0.13), and a known sender yielded a 6.3% greater response rate (OR = 0.73; 95% CI = 0.47-1.14; P = 0.16). Overall item completion was 98.2%; items missed per respondent ranged from 1 to 14 out of 50. Print format and sender recognition interacted in predicting completion rate (OR = 13.33; 95% CI = 3.10-57.4; P = 0.001); completion was higher for double-sided printing with an unknown sender, and for single-sided printing with a known sender. Completion was also lower when response came after later mailouts (chi2(2) = 10.13; P = 0.006).

Print format and sender recognition both yielded 6%-7% (nonsignificant) response rate differences. Survey completion rate varied even when overall item completion was high. Completion rate was useful for identifying subgroups likely to provide incomplete data (i.e., late responders), and may provide important information for subsequent surveys. Combining factors that on their own improve survey response may have unexpected consequences.