@techreport{oai:ir.ide.go.jp:00037596,
 author = {Keola, Souknilanh and Tsubota, Kenmei},
 month = {Mar},
 note = {application/pdf, IDP000589_001, There are conventional methods to calculate the centroid of spatial units and distance among them with using Geographical Information Systems (GIS). The paper points out potential measurement errors of this calculation. By taking Indian district data as an example, systematic errors concealed in such variables are shown. Two comparisons are examined; firstly, we compare the centroid obtained from the spatial units, polygons, and the centre of each city where its district headquarters locates. Secondly, between the centres represented in the above, we calculate the direct distances and road distances obtained from each pair of two districts. From the comparison between the direct distances of centroid of spatial units and the road distances of centre of district headquarters, we show the distribution of errors and list some caveats for the use of conventional variables obtained from GIS.},
 title = {Some notes on the spatial representations},
 year = {2016}
}