手法を比較

	Urban Primacy Index	Spatial Gini Concentration Index
分野	Human Geography	Human Geography
系統	Process / pipeline	Process / pipeline
提唱年	1939	1991
提唱者	Mark Jefferson	Corrado Gini (coefficient); locational adaptation in regional science / economic geography
種類	Index of the dominance of the largest city in an urban system	Descriptive index of how unevenly an activity is distributed across space
原典	Jefferson, M. (1939). The Law of the Primate City. Geographical Review, 29(2), 226–232.	Duncan, O. D., & Duncan, B. (1955). A methodological analysis of segregation indexes. American Sociological Review, 20(2), 210–217.
別名	Primacy Index, Primate City Index, Two-City Primacy Index, Four-City Primacy Index	Locational Gini Coefficient, Spatial Gini Index, Geographic Concentration Index, Gini Index of Spatial Inequality
関連	4	4
概要	The urban primacy index measures how dominant a country's largest city is relative to the cities below it in the size hierarchy. It grows out of Mark Jefferson's 1939 law of the primate city, which observed that many countries are headed by a single city far larger and more important than any other. The simplest two-city index divides the largest city's population by the second-largest's, while the four-city index compares the leading city with the combined size of the next three, giving a compact gauge of urban concentration.	The spatial (or locational) Gini concentration index adapts the classic Gini coefficient to geography, summarizing in a single number between zero and one how unevenly an activity — an industry, a population group, a resource — is distributed across spatial units relative to a benchmark such as total population or land area. It is the workhorse measure for quantifying geographic concentration and agglomeration in economic geography.