Background

SDI (Spatial Data Infrastructure) is the relevant base collection of technologies, policies and institutional arrangements that facilitate the availability of and access to spatial data (GSDI, 2001). The NGIS (National Geographic Information System) is a nation level SDI (NSDI) established by Taiwan government in 1990. Until 2015, 24 data standards and the TGOS (Taiwan Geospatial One Stop), a web service platform for data distribution and service, have been formulated and established. This NSDI has contributed to the efficacy of data sharing. However, social economic data was not included until 2006 because of the inherent nature of privacy concern. In 2006, a Census Geography system for demographic and social economic data was developed by the Ministry of Interior as a part of NSDI. It is a mechanism for demographic and social economic data to be associated with spatial location and aggregated by relevant spatial units (Tsai, et al., 2012). The system comprises a statistical area and six levels of dissemination areas for data provision in terms of different level of detail. This paper reports the promotion and applications of the census geography system. A typical example of actual price registration of real estate transaction is illustrated in details.

Promotion

Before the census geography system was established, demography and social economic data were aggregated by jurisdictional areas either in text form of digital format or in tabular form of report. Consequently, it is difficult to illustrate spatial distribution or variation of social economic status. However, people are accustomed to use this type of data for a long time. After the completion of implementing census geography system, the Ministry of Interior began to disseminate benefit of this new data form. There are 116 data items have been aggregated and distributed by either 1^st level or 2^nd level dissemination areas (Fig.1). Among those data items, 27 items were included in government's open data sets(data.gov.tw) for public use. A portal of the NGIS social economic data was established. Users are able to produce thematic maps online or download data for advanced analysis. 191590 data has been downloaded until April 2016. In addition, 86 workshops, seminars or forums were held in past five years.

Applications

In consequence, GIS practitioners and researchers are getting acquainted with the census geography system and begin to adopt these data on their professional works. Dengue fever prevention (Fig. 2), vulnerable people estimation (Fig.3), and population exposure assessment in potential flood area are significant examples. The price information of real estate transaction system is a newly established service. The real estate market for house or land is not transparent traditionally. Since real estate price rose accelerating in the past few years, the authority was requested to provide transaction price for better decision making when purchasing a house or land. However, privacy issue has to be taken into consideration. The original system moves the transaction location arbitrary to secure privacy (Fig. 4). In this case, the price may not reveal relevant information. The alternative method is to aggregate transaction prices by census geography. Figure 5 shows average transaction prices presented by the 2^nd dissemination area. The average price of a small area provides more accurate information than any single transaction event. People are able to make a better decision.

Conclusion

Census geography is a part of the Taiwan NSDI specific for demographic and social economic data. After the completion of the system implementation in 2012, the Ministry of Interior has put much efforts on promotion. GIS practitioners and researchers has begun to adopt this new form of data. Many applications have been conducted. The census geography system has proven to be beneficial to government decision-makers and researchers in terms of the discovery of spatial characteristics of demographic and social economic data. The privacy of individuals is secured as well.

Fig.1 Population Distribution by      Fig.2 Population Distribution in Dengue

1^st Dissemination Area               Hot Spots

Fig.3 Vulnerable People Estimation     Fig.4 Query of Real Estate Transaction

Fig.5 Average Transaction Price by the 2^nd Dissemination Areas

References

GSDI (2001) The SDI Cookbook, ver.2, in D. Nebert eds., Washington D.C.: SDI

Tseng, Ya-Ping, Lin, Mei-Chun and Su Ming-Daw (2014) Integrating Dengue Case into Spatial Statistical Area and Classification System for Hotspot Analysis, Journal of the Chinese Statistical Association, 52(3):379-396.

Tsai, Bor-Wen, Chen, Chin-Hong and Shen, Jeremy (2012) Establishment of the Census Geography in Taiwan, GSDI 13, Quebec: GSDI.

The Price Information of Real Estate Transaction System, Ministry of Interior,   http://lvr.land.moi.gov.tw/login.action