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Jipp curve is a term for a graph plotting the number (density) of telephones against wealth as measured by the Gross Domestic Product (GDP) per capita. The Jipp curve shows across countries that teledensity increases with an increase in wealth or economic development (positive correlation), especially beyond a certain income. In other words, a country's telephone penetration is proportional to its population's buying power.〔(Goodman, James (2003). Mobile telephones and social capital in Poland. A case study with Vodafone Group. Final Report, April 2003. ''Final version of the case study "Mobile telephones and social capital in Poland" - part of the Deliverable 12 (D12) of the project DEESD - Digital Europe: e-business and sustainable development''. (p. 25) ) (retrieved 20 October 2008)〕 The relationship is sometimes also termed Jipp Law or Jipp's Law. The Jipp curve has been called "()robably the most familiar diagram in the economics of telecommunications".〔 The curve is named after A. Jipp, who was one of the first researchers to publish about the relationship in 1963.〔Jipp, A. (1963). Wealth of nations and telephone density. ''Telecommunications Journal, July 1963,'' pp. 199-201.〕 The number of telephones was traditionally measured by the number of landlines, but more recently, mobile phones have been used for the graphs as well. It has even been argued that the Jipp curve (or rather its measures) should be adjusted for countries where mobile phones are more common that landlines, namely for developing countries in Africa.〔(Kelly, Tim (2005). Redrawing the Jipp Curve for Africa. Retraçons la courbe de Jipp pour l'Afrique. ''The Acacia Atlas'' ) (retrieved 20 October 2008)〕 The term has sometimes been used in analogy for other curves as well, for example as a "postal Jipp curve" plotting letters posted per capita and GDP per capita.〔(Kenny, Charles (2005). Reforming the posts: Abandonning the monopoly-supported postal universal service obligation in developing countries. ''AEI-Brookings Joint Center for Regulatory Studies. Related Publication 05-17''. (p. 1) ) (retrieved 16 August 2007)〕 == References == 〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Jipp curve」の詳細全文を読む スポンサード リンク
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