**3. Data Description**

### *3.1. Description of Smartcard Data*

The government of Seoul has been operating the AFC system such as the smartcard system since 2004. The transit fare from the origin to destination is charged based on the total distance traveled by buses, subways, or both. Within the AFC system, travelers can use any combination of transit modes [31]. Since the transit system in Seoul has been operating as a 100% smartcard system, it is possible to extract 99% of the transit trip information. The smartcard data in Seoul records about 20 million individual transit trips per day. Each individual item of information is classified with respect to 36 categories, including card ID, boarding station, alighting station, boarding time, alighting time, etc. With the smartcard data, it is possible to obtain the numbers of subway, bus, bus–bus transfer, and subway–bus transfer trips. Since the smartcard data in Seoul include all transit users' trips, it can be used to analyze transit efficiency by station area [27]. Among the 36 categories of smartcard data, 11 were used in this research. These 11 categories include the card ID, boarding station ID, alighting station ID, number of transfers, alighting time, alighting date, boarding time, boarding date, line ID, vehicle ID, and zone code. Table 1 shows the 36 categories of smartcard data in Seoul of which 11 were used in this research.

indicates the categories used in this research.

## *3.2. Description of Socio-Economic Data*

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The government of Seoul has been operating an open big-data portal since October 2013. This open big-data portal is an integrated data platform and provides the public with data about Seoul. Open big-data portal is available to anyone who has the desire to use it. The portal refers to all the data and information produced by public institutions such as public information. It facilitates communication and cooperation between all those interested. These open data are wide-ranging in scope, with information ranging from weather, geography, transportation, and food to historical documents and records. Open data related to socio-economic and environmental indicators are provided at the administrative and statistical aggregation district level. Seoul consists of 424 neighborhood areas, called dong, and each neighborhood is composed of one or more census areas. In this research, the census area unit is used to aggregate the population density, land value, number of households, and number of companies. There are 103,455 census area units in Seoul with an average area of 0.58 km2.