The clustering of the station areas must be reviewed with a revealed value because the accessibility index contains some uncertainty in the potential value. For this purpose, the efficiency index, which can be measured by the revealed value of subway riders, was applied. The efficiency index of subway riders represents how effectively a subway station is used under the given TOD factors. The efficiency index of subway riders for a station area was calculated using Data Envelopment Analysis (DEA),1 for which the density, the diversity, and the intermodal connectivity were used as inputs, and the number of subway riders was employed as the output. Of the basic analysis models of DEA, an ‘output-oriented BCC model with variable return to scale’ (Cooper, Seiford, & Tone, 2007)2 was selected for this research. The output-oriented BCC