Σύγκριση μεθόδων

	Place-to-Place Migration Model	Intervening Opportunities Model
Πεδίο	Migration Studies	Migration Studies
Οικογένεια	Regression model	Regression model
Έτος προέλευσης	1966	1940
Δημιουργός	Ira S. Lowry; (gravity antecedent: George K. Zipf)	Samuel A. Stouffer
Τύπος	Econometric origin-destination flow model	Spatial-interaction model of migration volume
Θεμελιώδης πηγή	Lowry, I. S. (1966). Migration and Metropolitan Growth: Two Analytical Models. Chandler Publishing, San Francisco. ISBN: 9780810200135	Stouffer, S. A. (1940). Intervening Opportunities: A Theory Relating Mobility and Distance. American Sociological Review, 5(6), 845-867.
Εναλλακτικές ονομασίες	Origin-Destination Migration Model, Lowry Migration Model, Econometric Gross-Flow Model, Modified Gravity Migration Model	Stouffer Intervening Opportunities, Opportunity-Based Migration Model, Law of Intervening Opportunities
Συναφείς	3	3
Σύνοψη	The place-to-place migration model explains and predicts the gross number of people moving from each origin region to each destination region as a function of conditions at both ends and the distance between them. It descends from the gravity analogy popularized by George Zipf in 1946, in which movement between two cities rises with the product of their populations and falls with the distance separating them, but it adds behavioral economic content. Ira Lowry's 1966 formulation is the canonical example: he modeled interregional migration as driven by relative labor-market conditions — wages, unemployment, and the size of the labor force at origin and destination — modified by distance, and estimated the relationship econometrically from observed flows. Cast in log-linear or, in modern practice, Poisson form, the model recovers interpretable elasticities showing how flows respond to a wage gap or an unemployment differential, and it can reproduce or forecast the entire origin-destination matrix. It bridges the descriptive gravity tradition and explicit regression-based migration econometrics, and remains a workhorse for analyzing why people move where they do.	The intervening opportunities model, introduced by Samuel Stouffer in 1940, explains the volume of migration between two places not by the physical distance separating them but by the number of opportunities available at the destination relative to the opportunities a migrant would encounter along the way. Its central claim is provocative: there is no necessary relationship between mobility and distance. Distance only matters because crossing more of it usually means passing more chances to stop. Formally, the number of people moving a given distance is directly proportional to the number of opportunities at that distance and inversely proportional to the number of intervening opportunities. Stouffer revised the model in 1960 to add 'competing migrants' — rivals converging on the same destination from other origins — giving spatial-interaction analysis an alternative to the gravity model that is grounded in opportunity structure rather than mass and distance.