AHP (Analytical Hierarchy Process) is one of the most popular methods to model decision making process. AHP was worked out by Thomas L. Saaty, a professor of the University of Pittsburgh, and is used to model various type of social decision making process today. But most of the previous studies are focused on individual decision making and there are few studies which are focused on group decision making process. In this study, we review previous studies of AHP focused on group decision making and discuss about issues of them. Additionally, we propose how to improve previous models using pseudorandom numbers. We also apply our proposal to the development of product design in restoration business and confirm effectiveness of our proposal.

Until now, research on business models has focused on the theoretical aspects instead of case studies, with studies being mainly concerned with the constituent elements that make up business models. Accordingly, we look at a partwork magazine as an example of a unique and successful business model, examining it in detail, based on interviews with the publishing company Kodansha and on secondary data.

A partwork magazine is a publication created to cover a specific subject, published weekly or biweekly with a full run consisting of roughly 50 or 100 issues.

Specifically, we first look at the definitions of business models and prior studies on the subject, and then examine the magazine’s business model. We then present the essence of this business model, use sales data to verify and examine a part of this essence, and analysis the profit structure.

In recent Web services, network externality plays an important role. This effect, however, is not understood quantitatively enough either empirically or theoretically. To analyze the features of recent Web based services such as the spread of Social Networking Services, it is important to understand how the services grow under the effect of network externality.

In this paper, we first study the development of the number of users of several IT services in which network externality plays an important role. We then use Ising model to obtain the macroscopic quantities such as the number of users based on the parameters that give the consumption of each user. It is shown that the development of the number of users can be explained and that the dependency on the parameters in the model is small. This can be used for the IT firms to estimate the demand and optimize the investment.