Publication of land price information through the comparison of interpolated appraised prices and transaction prices

The Japanese are becoming increasingly aware of the significance of the disclosure of in-depth land price data with regard to establishing land markets with a high level of transparency and fairness. Presently, both the Public Notice of Land Prices, which essentially comprises values that are appraised by Japan's Ministry of Land, Infrastructure, Transport and Tourism, and transaction prices, which have been open to the public since 2005, play a major role in land pricing in Japan. However, these datasets alone do not provide adequate information for all market participants, not only because both are limited in number but also because they are specific to the situation in Japan: the appraised prices are always shown to be cheaper than the actual transaction prices, to a certain degree, and the important information with transactions such as the precise point in space and time is not completely open to the public owing to privacy protection. Furthermore, it is difficult to compare these two prices in a simple way as their distribution of points is different. In this paper, we propose the publication of valuable land price information by interpolating appraised prices to every transaction point by using the kriging method, comparing actual transaction prices with them, and drawing a map that allows us to understand the trend of land prices easily. Moreover, we build the experimental WebGIS service using which anyone can easily search the interpolated appraised price of the land of their interest and the related land price history and market conditions.