Migrants looking for opportunities - On destination size and spatial aggregation in the gravity equation for migration

Persyn, Damiaan (2021): Migrants looking for opportunities - On destination size and spatial aggregation in the gravity equation for migration.

Abstract

I consider a RUM model for migration where destination countries or regions are viewed as collections of ‘opportunities’ which are the fundamental units of choice for migrants. The best opportunity for a prospective migrant is more likely to be found in a destination that has many and diverse opportunities. Recent contributions in economics studying migration rather consider entire regions or countries as the fundamental, atomistic, units of choice. The key role of the size of destinations and the diversity within them is therefore often not fully recognised, which may lead to biased inference. I argue that the coefficient on size equals 1 in the ideal RUM model. This is also required for the gravity model for migration to have some intuitive properties: only then migration flows scale proportionally when aggregating destinations, and there is zero net migration between otherwise similar regions of different size. Models omitting size or using a coefficient on size different from 1 violate these properties. Imposing proportional scaling also has implications for how different sets of opportunities should be combined. The approach is showcased in a study of internal migration and urbanisation in Ethiopia.

• Item Type: MPRA Paper
• Language: English
• Keywords: migration, regional economics, spatial modelling, gravity equations, discrete choice
• Subjects: C - Mathematical and Quantitative Methods > C2 - Single Equation Models ; Single Variables > C25 - Discrete Regression and Qualitative Choice Models ; Discrete Regressors ; Proportions ; Probabilities; F - International Economics > F2 - International Factor Movements and International Business; R - Urban, Rural, Regional, Real Estate, and Transportation Economics > R2 - Household Analysis > R23 - Regional Migration ; Regional Labor Markets ; Population ; Neighborhood Characteristics

References

Anas, A. (1983): “Discrete choice theory, information theory and the multinomial logit and gravity models,” Transportation Research Part B: Methodological, 17(1), 13–23.

Anderson, J. E., and E. V. Wincoop (2003): “Gravity with Gravitas: A Solution to the Border Puzzle,” The American Economic Review, 93(1), 23.

Beine, M., S. Bertoli, and J. Fernández-Huertas Moraga (2016): “A Practitioners’ Guide to Gravity Models of International Migration,” The World Economy, 39(4), 496–512.

Beine, M., M. Bierlaire, and F. Docqier (2021): “New York, Abu Dhabi, London or Stay at Home? Using a Cross-Nested Logit Model to Identify Complex Substitution Patterns in Migration,” IZA Discussion Pap er, 14090.

Beine, M., P. Bourgeon, and J. Bricongne (2019): “Aggregate Fluctuations and International Migration,” The Scandinavian Journal of Economics, 121(1), 117–152.

Berry, S. T. (1994): “Estimating Discrete-Choice Models of Product Differentiation,” The RAND Journal of Economics, 25(2), 242–262.

Bertoli, S., and J. Fernández-Huertas Moraga (2013): “Multilateral resistance to migration,” Journal of Develop ment Economics, 102, 79–100.

Bertoli, S., J. F.-H. Moraga, and L. Guichard (2020): “Rational inattention and migration decisions,” Journal of International Economics, 126, 103364.

Bierlaire, M. (2020): “A short introduction to PandasBiogeme,” in Technical rep ort

TRANSP-OR 200605. Transp ort and Mobility Laboratory, ENAC, EPFL.

Borjas, G. J. (1987): “Self-Selection and the Earnings of Immigrants,” The American Economic Review, 77(4), 531–553.

Bundervoet, T. (2018): “Internal Migration in Ethiopia, Evidence from a Quantitative and Qualitative Research Study,” World Bank, Washington, DC.

Cardell, N. S. (1997): “Variance Components Structures for the Extreme-Value and Logistic Distributions with Application to Models of Heterogeneity,” Econometric Theory, 13(2),185–213.

Daly, A. (1982): “Estimating choice models containing attraction variables,” Transportation Research Part B: Methodological, 16(1), 5–15.

Davies, R. B., and C. M. Guy (1987): “The Statistical Modeling of Flow Data When the Poisson Assumption Is Violated,” Geograp hical Analysis, 19(4), 300–314.

Docqier, F., G. Peri, and I. Ruyssen (2014): “The Cross-country Determinants of Potential and Actual Migration,” International Migration Review, 48(1_suppl), 37–99.

Fally, T. (2015): “Structural gravity and fixed effects,” Journal of International Economics, 97(1), 76–85.

Flowerdew, R., and M. Aitkin (1982): “A Method of Fitting the Gravity Model Based on the Poisson Distribution,” Journal of Regional Science, 22(2), 191–202.

Fotheringham, A. S., and P. A. Williams (1983): “Further Discussion on the Poisson Interaction Model,” Geographical Analysis, 15(4), 343–347.

Griffith, D. A., and M. M. Fischer (2013): “Constrained variants of the gravity model and spatial dependence: model specification and estimation issues,” Journal of Geographical Systems, 15(3), 291–317.

Grogger, J., and G. H. Hanson (2011): “Income maximization and the selection and sorting of international migrants,” Journal of Develop ment Economics, 95(1), 42–57.

Harris, J. R., and M. P. Todaro (1970): “Migration, unemployment and development: a two-sector analysis,” The American economic review, pp. 126–142.

Kanaroglou, P. S., and M. R. Ferguson (1996): “Discrete Spatial Choice Models for Aggregate Destinations,” Journal of Regional Science, 36(2), 271–290.

McFadden, D. (1974): “The measurement of urban travel demand,” Journal of Public Economics, 3(4), 303–328.

McFadden, D. (1977): “Modelling the Choice of Residential Location,” Cowles Foundation Discussion Papers, 477.

Ortega, F., and G. Peri (2013): “The Role of Income and Immigration Policies in Attracting International Migrants,” Migration Studies, 1(1), 47–74.

Persyn, D., and W. Torfs (2016): “A gravity equation for commuting with an application to estimating regional border effects in Belgium,” Journal of Economic Geograp hy, 16(1),155–175.

Silva, J. M. C. S., and S. Tenreyro (2006): “The Log of Gravity,” Review of Economics and Statistics, 88(4), 641–658.

Stark, O. (2006): “Inequality and migration: A behavioral link,” Economics Letters, 91(1), 146–152.

Train, K. (2002): Discrete Choice Methods with Simulation. Cambridge University Press.

Wilson, A. (1967): “A statistical theory of spatial distribution models,” Transportation Research, 1(3), 253–269.

Wilson, A. (1970): Entropy in urban and regional modelling. London: Pion.

Wilson, A. (1971): “A family of spatial interaction models, and associated developments,” Environment and Planning, 3, 32.