Finally, the value added from combining multiple sources of information highlights the importance of  reliable administrative boundaries. Digitized administrative boundaries the polygons delimiting the  jurisdiction of cities, towns, and villages are the true anchor of data integration. They can be used as the basis for combining information from different sources and for establishing ground truth. But for this approach to work, credible digitized files (often in the form of shapefiles) are needed for the lowest layers of the administrative hierarchy of a country. However, this issue is often overlooked by modern approaches based on remote sensing technology.

# **References**

- <mark>Ahlfeldt, Gabriel M., Stephen J. Redding, Daniel M. Sturm, and Nikolaus Wolf. 2015. “The Economics of Density: Evidence from the Berlin Wall.”</mark> _<mark>Econometrica</mark>_ <mark>83 (6): 212789.</mark>

- <mark>Alonso, W. 1964. “Location and Land Use: Toward a General Theory of Land Rent.” Harvard University, Cambridge, MA.</mark>

- <mark>Bilger, Marcel, and Willard G. Manning. 2015. "Measuring Overfitting in Nonlinear Models: A New Method and an Application to Health Expenditures."</mark> _<mark>Health Economics</mark>_ <mark>24 (1): 75–85.</mark>

- <mark>Bontemps, S., P. Defourny, E. V. Bogaert, O. Arino, V. Kalogirou, and J. R. Perez. 2011. "GLOBCOVER 2009 Products Description and Validation Report.” Google Scholar.</mark>

<mark>Breiman, Leo. 2001a. "Random Forests."</mark> _<mark>Machine Learning</mark>_ <mark>45 (1): 5–32.</mark>

- <mark>___________. 2001b. "Statistical Modeling: The Two Cultures (with comments and a rejoinder by the author)."</mark> _<mark>Statistical Science</mark>_ <mark>16 (3): 199–231.</mark>

<mark>Brookings Institution. 2015.</mark> _<mark>Global Metro Monitor 2014.</mark>_ <mark>Washington, DC: Brookings.</mark>

- <mark>Brueckner, J. K. 1987. “The Structure of Urban Equilibria: A Unified Treatment of the Muth‐Mills Model.”</mark> _<mark>Handbook of Regional and Urban Economics,</mark>_ <mark>Vol. 2, edited by E. S. Mills, 821–45. Amsterdam: North‐Holland.</mark>

- <mark>Burchfield, M., H. G. Overman, D. Puga, and M. A. Turner. 2006. “Causes of Sprawl: A Portrait from Space.”</mark> _<mark>Quarterly Journal of Economics</mark>_ <mark>121 (2): 587–633.</mark>

- <mark>Cameron, A. Colin, and Pravin K. Trivedi. 2005.</mark> _<mark>Microeconometrics: Methods and Applications</mark>_ <mark>. Cambridge, U.K.: Cambridge University Press.</mark>

- <mark>Combes, Pierre‐Philippe, Gilles Duranton, Laurent Gobillon, and Sébastien Roux. 2010. “Estimating Agglomeration Economies with History, Geology, and Worker Effects.” In</mark> _<mark>Agglomeration Economics,</mark>_ <mark>edited by Edward L. Glaeser, 15–66. Chicago: University of Chicago Press.</mark>

- <mark>Copas, John B. 1983. "Regression, Prediction and Shrinkage."</mark> _<mark>Journal of the Royal Statistical Society.</mark>_ <mark>Series B (Methodological): 311–54.</mark>

- <mark>Davis, Donald, Jonathan Dingel, and Antonio Miscio. 2018. “Cities, Skills, and Sectors in Developing Economies.”Paper presented at 8th European Meeting of Urban Economics Association, Düsseldorf, Germany, May 11.</mark>

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