動画共有サイトにおける大規模な協調的創造活動の創発のネットワーク分析 ニコニコ動画における初音ミク動画コミュニティを対象として Summary: The Web technology enables numerous people to collaborate in creation. We designate it as massively collaborative creation via the Web. As an example of massively collaborative creation, we particularly examine video development on Nico Nico Douga, which is a video sharing website that is popular in Japan. We specifically e