Do incentives, reminders or reduced burden improve healthcare professional response rates in postal questionnaires? two randomised controlled trials

Table 5 Response rates and Costs by option

	Response rate	Average costs	Incr RR	Incr costs	Cost per additional response
Qxx	0.23	£ 3.61	0.23	£ 3.61	£15.71 per response
Qpx	0.29	£ 4.96
QQx	0.31	£ 6.15
QpQ	0.33	£ 7.17
QQQ	0.36	£ 8.09
QQq	0.36	£ 7.59
Qpq	0.42	£ 6.71	0.19	£ 3.10	£15.99 per response

ISSN: 1472-6963