Network effects are an important factor in the development of the information and communications industry. In previous research, the size of the network has been specified as the total number of users of goods and services, and there is no attention to the constituent users of the network. Therefore, in this research, we focus on the possibility that the network effect varies depending on its constituent users, and build a model in which the number of paying users and the number of non-paying users have different influences on the use of mobile games, respectively, and analyze them.

As a result of the analysis, it was found that the number of paying users significantly affected the payment amount, and when the paying users increased 1%, the payment amount increased by 0.06%. On the other hand, the number of non-paying users did not appear to have an influence. From this, it is suggested that the network effect differs depending on its constituent users, and the network effect of non-paying users is limited.

Many candidates utilized social media such as Facebook and Twitter for their election campaign in the 2014 election. On the other hand, since social media use during election campaigns had been prohibited until 2013 in Japan there are few literatures focusing on the tendencies and effectiveness of social media use by candidates. Moreover, literatures and news articles have usually focused on comparison among political parties and didn't pay much attention on candidates.

This research tries to examine usage tendencies of candidates of Twitter use empirically by using original sampling data. Especially, we focus on past actual use and clarify immature use of social media.

In the European Union, the regulations on online platforms are under discussion. In this context, in May 2016, the European Commission proposed the Directive amending the Audiovisual Media Services Directive, which would impose new regulations on video-sharing platforms. It is considered that videoplatform providers should duly determine their "organisation" such as by sequencing in order to safeguard citizens and minors from illegal and harmful contents. This would cause a significant discussion about the liability of video-platform providers as intermediaries and the free flow of information.