Abstract:     As time-based competition becomes fiercer and fiercer, more and more firms recognize the greatest importance of open innovation and have taken users as their one of the most important external innovation sources. During the course of a firm′s innovation, user participation provides a firm a new avenue to achieve higher new product development (NPD) performance. However, a firm involving users into its innovative activities will face the challenge of how to adapt the traditional organizing processes to meet the need of open innovation, for a firm has to have its some innovation processes opened to users which will bring out some additional managerial costs and risks. In turn, it will determine whether a firm could make good advantages of the potential values created by users to achieve higher innovation performance effectively or not. That means that a firm has to handle the balance between benefits from openness of innovative processes on the one side and the loss from more complex coordination originated from openness on the other side, for that users are not only the most important innovation sources, but also the most uncertainty input for a firm′s operation. The extant literature has not got the consensus on the question mentioned above. This paper tries to address this problem systematically.
   Firstly, according to roles played differently in participation and the depth of users′ participation, the present research identifies the users′ participation into a firm′s innovative activities as three different modes, namely, a user participating as an independent innovator, information provider, or co-developer. Based on that categorization, the research is expected to explore whether there are differences in different modes of users′ participation effecting on a firm′s NPD performance and how do those effects happen? Based on the reviews of the theories of innovation and organization, we propose the hypotheses that users′ participation will help a firm to get higher NPD performance, no matter which participative mode a firm decides to adopt. Because users′ participation as co-developer will provide more chances to share knowledge, in particular the tacit knowledge, which will be conducive to mitigating the problem generated from information stickiness, we assume that the effect of users′ participation as co-developer on NPD performance is stronger than that of users′ participation as information provider and as an innovator, respectively. Furthermore, in order to make good advantages of users′ potential value as a firm′s external innovation sources, boundary-spanning coordinative practices which are played as a mediator are needed to link user participation and a firm′s NPD performance. 
   Using data collected from 444 Chinese firms, all hypotheses have been tested and main results got: A firm may leverage its new product development (NPD) performance via the strategy of adopting users to participate in its process of NPD. Different way that user choose to participate in a firm′s innovation has different effect on a firm′s NPD performance, namely, user participation as information provider contributes more to a firm′s NPD performance than both that of user as co-developer and that of user as innovator do. Furthermore, different ways of user participating in a firm′s innovation effect a firm′s NPD performance via different organizational processes. Our findings highlight that a firm has to make a balance between the benefits and the costs both originating from a firm′s open innovation to its users. Boundary-spanning coordination play the role of mediator in the relationship between user participation and NPD performance. Most of all, it is the key that the formal coordination, namely, cross-functional coordination mediates the relationship between user participation as an innovator and NPD performance completely, or the effect will be negative for the focal firm. 
   Taking the perspective of trading-off between the management costs originated from innovation process openness to users and the benefits generated from value creation process′s closure, the present paper deepens the extant literature of open innovation, user innovation and users′ participation. Our theoretical contributions are concluded as follows: (1) The micro-processes of users′ participation effecting on firms′ NPD performance has been disclosed, which makes us understand the mechanism of how users′ participation influence a firm′s NPD performance more deeply. To profit from users′ participation, a firm has to learn to balance between the costs and benefits originated from users′ participative activities. (2) Insights of different modes of uses′ participation influencing a firm to achieve NPD performance via different paths are provided. In particular, the mode of users′ participation as an innovator will not do good to help a firm get higher NPD performance unless a formal boundary-spanning coordination mechanism is designed to introduce the external innovator into a firm′s NPD process, which highlights the key role of organization design and practices in a firm involving its users in innovation processes to make good advantages of users′ potential value. Our findings provide a systematic framework to guide the practice.
   Finally, we discuss the limitations and future research. For the reason of convenience and availability, we collected data mostly in Anhui Province, which may make the results be limited in generalizability. And we adopted the cross-sectional design to conduct this research. As known to all, the shortage of cross-sectional design is not good enough to make cause-effect deduction. However, we have tested the mediating role of boundary-spanning coordination in the relationship between user participation and NPD performance, which implies the cause-effect hypothesis. As a result, we plan to collect more data from different provinces, especially those provinces with more actively innovative activities′ firms on the one side. And on the other side, we will try to enter into some typical firms which practice co-creation with users, to conduct case studies. We believe those attempts will provide us with more holistic and deeply insights.

Key words: user participation, boundary-spanning coordination, NPD, user innovation