เปรียบเทียบวิธี

	Clark Density Model	Accessibility Analysis
สาขาวิชา	Human Geography	Human Geography
ตระกูล	Regression model	Process / pipeline
ปีกำเนิด	1951	1959
ผู้ริเริ่ม	Colin Clark	Walter G. Hansen
ประเภท	Empirical regression model of urban population density decline with distance	Spatial index of the ease of reaching opportunities from a location
แหล่งต้นตำรับ	Clark, C. (1951). Urban population densities. Journal of the Royal Statistical Society. Series A (General), 114(4), 490–496.	Hansen, W. G. (1959). How accessibility shapes land use. Journal of the American Institute of Planners, 25(2), 73–76.
ชื่อเรียกอื่น	Clark's Law, Negative-Exponential Density Model, Exponential Population Density Gradient, Clark Density Gradient	Hansen Accessibility, Gravity Accessibility Measure, Potential Accessibility, Spatial Accessibility Index
ที่เกี่ยวข้อง	4	4
สรุป	The Clark density model is the classic empirical description of how urban population density falls with distance from the city centre, formulated by the economist Colin Clark in 1951. It states that density declines exponentially outward from a central peak, so that plotting the logarithm of density against distance yields a straight line whose slope is the density gradient. This negative-exponential 'law' became the standard model of urban spatial structure and the empirical foundation for later monocentric-city theory.	Accessibility analysis measures how easily opportunities — jobs, shops, clinics, parks — can be reached from a given location, combining the attractiveness (size) of destinations with the cost of travelling to them. The gravity-based formulation introduced by Walter Hansen in 1959 sums the opportunities at all destinations, each discounted by a distance-decay function of travel cost, producing a single accessibility score per origin that has become a foundational concept in transport geography and urban planning.