Asch D A, Christakis N A, Ubel P A
Veterans Affairs Medical Center, Philadelphia, PA, USA.
Med Care. 1998 Jan;36(1):95-9. doi: 10.1097/00005650-199801000-00011.
The effects of incentive size on physicians' response rates to a mail survey were determined.
One thousand US primary care physicians were assigned randomly to receive a survey with either a $5 bill or a $2 bill as an incentive. For each of the two incentive groups, the overall response rate for three mailing waves, the total cost, and the total cost per usable response were measured.
The response rate among those receiving the $5 bill (61%) was 32% higher than the response rate among those receiving the $2 bill (46%); overall costs were slightly higher in the $5 group, but the cost per response for each group was similar ($15.46 versus $14.93). For the same cost, a higher response rate could have been achieved in the $2 group if costs saved from foregoing the third mailing were instead used to increase the incentive for a portion of the subjects.
A $5 bill incentive yielded a higher response rate among the physicians in this study than did a $2 bill incentive. Moreover, the powerful effect of the incentive size, combined with the consequent decline in the costs of subsequent mailing waves, suggests that resources in a fixed survey budget are allocated more efficiently to increasing the initial incentive rather than to providing a third wave to nonresponders.
确定激励金额对医生邮件调查回复率的影响。
将1000名美国初级保健医生随机分为两组，分别收到附带5美元或2美元激励的调查问卷。对两个激励组中的每一组，测量三轮邮件发放的总体回复率、总成本以及每份有效回复的总成本。
收到5美元的组的回复率（61%）比收到2美元的组的回复率（46%）高32%；5美元组的总体成本略高，但每组每份回复的成本相似（15.46美元对14.93美元）。对于相同的成本，如果将省去第三次邮件发放节省的成本用于增加部分受试者的激励，2美元组本可以实现更高的回复率。
在本研究中，5美元的激励比2美元的激励在医生中产生了更高的回复率。此外，激励金额的强大作用，再加上后续邮件发放成本的相应下降，表明固定调查预算中的资源更有效地分配用于增加初始激励，而不是用于向未回复者提供第三次邮件发放。
