How open should an open system be? : essays on mobile computing

"Systems" goods-such as computers, telecom networks, and automobiles-are made up of multiple components. This dissertation comprises three essays that study the decisions of system innovators in mobile computing to "open" development of their systems to outside suppliers and the implications of doing so. The first essay considers this issue from the perspective of which components are retained under the control of the original innovator to act as a "platform" in the system. Based on detailed review of leading systems in this industry in data spanning 1984-2004, I find that platform boundaries expand and contract over time as a means for platform suppliers to promote the adoption of the platform (by end-customers, downstream manufacturers, and suppliers of complements) and simultaneously to ensure the continuing innovation of the system. The second essay provides a systematic empirical investigation of how the extent of openness chosen by the platform supplier affected the rate of innovation of mobile computing devices. I measure openness in relation to both the boundaries of the platform and the extent to which actions were taken by platform suppliers to promote entry by hardware device manufacturers.