Compare methods

	Gravity Model of Migration	Central Place Analysis
Field	Human Geography	Human Geography
Family	Regression model	Process / pipeline
Year of origin	1946	1933
Originator	George Kingsley Zipf (formalized); analogy to Newton's law of gravitation	Walter Christaller
Type	Spatial-interaction regression model for migration flows	Theory and analytic framework for the size, number, and spacing of settlements
Seminal source	Zipf, G. K. (1946). The P1 P2 / D hypothesis: On the intercity movement of persons. American Sociological Review, 11(6), 677–686.	Christaller, W. (1966). Central Places in Southern Germany (C. W. Baskin, Trans.). Prentice-Hall. (Original work published 1933). ISBN: 9780131226302
Aliases	Migration Gravity Model, Demographic Gravity Model, Zipf P1P2/D Model, Gravity Model of Spatial Interaction (Migration)	Central Place Theory, Christaller Central Place Model, Settlement Hierarchy Analysis, Central Place Hierarchy
Related	4	4
Summary	The gravity model of migration explains the volume of movement between two places as proportional to the product of their populations (masses) and inversely proportional to the distance separating them, by direct analogy to Newton's law of universal gravitation. Formalized for intercity movement by George Kingsley Zipf in 1946 and embedded in regional science by Walter Isard, it is the workhorse model of human geography for predicting migration, commuting, and other spatial-interaction flows.	Central place analysis is the study of the size, number, and spacing of settlements as service centres, grounded in Walter Christaller's central place theory of 1933. It explains why settlements form an orderly hierarchy — many small villages, fewer towns, a handful of cities — and why higher-order centres are spaced farther apart and offer more specialized goods, deriving the famous nested pattern of hexagonal market areas from two economic concepts: the range and the threshold of a good.