EMPIRICAL STUDY ON REGIONALLY EXTERNAL ECONOMIES BASED ON GIS
研究了外部经济不仅存在于城市点状空间，还扩展到区域范围，通过芝加哥和洛杉矶的就业数据验证了区域外部经济的存在。
Agglomeration has been the focus of both economists and geographers,even though it has existed since urban appeared thousands years ago,however urban is not the only pattern of agglomeration.With the change of current social and economic situation,extensive patterns of 'urbanized regions' like polycentric urban,metropolitan complex or conurbation and megalopolis are becoming normal status as an agglomeration,so urbanized regions could not be taken into account for the traditional externality economies,which is typically represented by the Marshall's trinity externality economies.Based on the dynamic externality economies study by both economists and geographers the paper presents some research work on external economies spatially with the conclusion of external economies not only work in the spatial of 'spot' but also in the extensive territory,namely there exist the regional external economies,which refers to the fact that the advantages customarily associated with externality-based agglomeration economies are actually available to the relevant firms throughout(or over a significant part of) a given region.Even though some scholars like N.A.Phelps and B.J.Parr identified the concept of regional external economies,however they didn't present the empirical proof to support their ideas.The paper is trying to applying the concept to test both in Illinois and California states where Chicago of classical monocentric metropolitan and Los Angels of polycentric metropolitan locate.The two states are chosen because of Chicago and L.A representing two different spatially development pattern,which could cover almost all the types of metropolitans.In order to check the regional external economies exists or not,the hypothesis is employment change has not any different between the range 20km and the range 20km-70km away from the central city during 1990-2000 if the regional external economies works initially,otherwise the employment change differently between the above two ranges since the monetary externality and technology externality spatial diffuse differentially if the external economies expand to more spatially regions with the time goes.GIS method and Geoda software are applying here to examine the spatial evolving of monetary external economies and technology external economies.The result shows that the two employment change do happen in the two different states where Chicago and L.A metropolitan dominant,which verify the regional external economies existing both in initial and evolvable term.The empirical work on Shanghai from other scholars also support the result.