Table 1.

Respondents before and after each reminder in the two randomised groups, and final response rates

	Group A (n=4760)	Group B (n=1694)
Respondents before reminder
Electronic, n	272	117
Paper, n	560	–
Response rate, %	17.5	6.9
Respondents after first reminder
Electronic, n	171	126
Paper, n	533	–
Increase in response rate, %	14.8	7.4
Respondents after second reminder
Electronic, n	148	67
Paper, n	345	–
Increase in response rate, %	10.4	4.0
Total
Electronic, n (%)	591 (29.1)	310
Paper, n (%)	1438 (70.9)
Response rate, %	42.6	18.3