Abstract: How to motivate voluntary contribution is vital for keeping online community (OC) vibrant Recently, scholars start to identify the impacts of monetary incentives on voluntary contribution in OC. but few researches have been conducted on multi-sided platforms. Leveraging a natural experimental design, this paper investigates the impact of paid service channel (telephone consultation service) on voluntary contribution of physicians in a service dominant online community-online healthcare community (OHC).The results indicate that after receiving telephone consultations, physicians exert more efforts on free text consultation services to provide more timely and detailed medical advices. Meanwhile, the motivating effect of telephone consultation varies across physicians with different levels of social interactions. Compared to physicians with a high level of social interaction, physicians with a low level of social interaction exert more efforts on free text consultation service after receiving telephone consultations. The previous research on the impacts of monetary incentives on voluntary contribution in OC are mainly based on product dominant communities, this paper extends monetary incentives to service dominant two-sided online platforms. Using a natural experimental design, it identifies causal impact of monetay incentive and heterogeneity across physicians which could help policy making on platform design and governance.

Key words: online healthcare community (OHC), monetary incentive, voluntary contribution, natural experiment, difference-in-difference

摘要： 如何激励用户自愿贡献知识是保持在线社区活跃度的关键。近年来, 学者开始探讨有偿激励对在线社区自愿贡献的影响。然而, 较少有研究分析多边平台下的有偿激励的溢出效应。借助于自然实验的设计, 考虑一种服务主导型在线社区———在线健康社区中, 服务提供者(即医生) 开通有偿服务(电话咨询) 渠道对其知识贡献行为的影响。研究发现：开通有偿服务后,医生会在原来的免费文本咨询服务上也花费更多努力, 提供更多、更及时和详实的医疗建议。同时, 有偿服务对医生知识贡献的激励作用因医生社交互动程度而不同。相对于社交互动多的医生, 社交互动少的医生开通电话咨询后, 文本咨询努力程度的增加更明显。以往有关有偿激励对在线社区自愿贡献的影响多基于单边平台中产品主导型激励, 该研究将有偿激励拓展至服务主导型的双边平台场景中。采用自然实验的设计, 探索有偿激励对自愿贡献的因果关系及异质性, 为平台设计和治理提供参考。

关键词: 在线健康社区, 金钱激励, 自愿贡献, 自然实验, 双重差分