Migration is the principal demographic process shaping patterns of human settlement, and it serves an essential role in human development. While progress has been made in measuring international migration, internal migration statistics are as yet poorly developed in many countries. This article draws on a repository of data established under the IMAGE (Internal Migration Around the GlobE) project to address this deficit by constructing the first comprehensive league table of internal migration intensities for countries around the world. We review previous work, outline the major impediments to making reliable comparisons, and set out a methodology that combines a novel estimation procedure with a flexible spatial aggregation facility. We present the results in the form of league tables of aggregate crude migration intensities that capture all changes of address over one‐year or five‐year intervals for 96 countries, representing four‐fifths of the global population. Explanation for the observed differences has been sought, inter alia, in historical, structural, cultural, and economic forces. We examine the links between development and migration intensity through simple correlations using a range of demographic, economic, and social variables. Results reveal clear associations between internal migration intensities and selected indicators of national development.

We know that internal migration shapes human settlement patterns, but few attempts have been made to measure systematically the extent of population redistribution or make comparisons between countries. Robust comparisons are hampered by limited data access, different spacetime frameworks, and inadequate summary statistics. We use new analysis software (IMAGE Studio) to assess the effects of differences in the number and configuration of geographic zones and implement new measures to make comparisons across a large sample of countries, representing 80% of global population. We construct a new Index of Net Migration Impact to measure system-wide population redistribution and examine the relative contributions of migration intensity and effectiveness to crossnational variations. We compare spatial patterns using the slope of a regression between migration and population density across zones in each country to indicate the direction and pace of population concentration. We report correlations between measures of population redistribution and national development and propose a general theoretical model suggesting how internal migration redistributes population across settlement systems during the development process.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Figure 1. Migration intensity, migration effectiveness and the aggregate net migration rate, as a function of the number of spatial units, selected countries that measure migration over a 5-year interval. 8 of 22 P. Rees et al.

Despite underlying regularities in the age profile of migration, there is mounting evidence of cross‐national variations in the ages at which migration occurs. Explanations for these differences have variously been sought by reference to cultural, social, and economic factors, and through analysis of reasons for moving. There is also a growing body of work linking migration events to particular transitions in the life course. We set out a conceptual framework that links contextual factors to the age structure of migration through life‐course transitions that act as proximate determinants of the age at migration. We propose metrics to capture the prevalence, timing, and spread of four key life‐course transitions: education completion, labor force entry, union formation, and first childbearing. We then seek to quantitatively establish the link between these indicators and the age and intensity of internal migration at its peak for a global sample of 27 countries. Correlation and factor analysis reveal substantial diversity in the timing and spread of transitions to adult roles, and show that cross‐national differences in the age profile of migration closely parallel variations in the age structure of the life course for over two‐thirds of countries. Migration age profiles are aligned with transitions to adulthood for both sexes but most strongly among women.

Compared with other demographic processes, little attention has been given to the way levels and patterns of internal migration vary around the world. This can be traced in part to the absence of any central repository of internal migration data, but it also reflects widespread variation in the ways migration is measured. If robust, reliable comparisons between countries are to be made, a clear understanding of the available data is an essential pre‐requisite. This paper reports results from the Internal Migration Around the GlobE project, which established an inventory of internal migration data collections for the 193 UN member States, identifying, inter alia, the types of data collected, the intervals over which it is measured and the spatial frameworks employed. Results reveal substantial diversity in data collection practice. We assess the strengths, limitations, and utility of the six principle ways migration is measured and examine their capacity to address key questions and issues in the field. We also identify avenues for harmonisation and conclude with recommendations which aim to facilitate cross‐national comparisons. Copyright © 2014 John Wiley & Sons, Ltd.

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We develop and demonstrate the application of a concise set of measures intended to encapsulate key features of the age profile of internal migration and highlight the significant differences that exist between nations in these profiles. Model schedules have been the most common method of comparing internal migration patterns but issues related to the estimation and interpretation of their parameters hinder their use for cross-national comparison. We demonstrate that the interpretation of exponential coefficients as rates of ascent and descent does not best reflect the slopes of migration age profiles, and we propose more consistent measures based on the rate of change in migration intensity. We demonstrate, through correlation and factor analysis, that most of the inter-country variance in migration age profiles is captured by the age at and intensity of peak migration. The application of these two indicators to 25 countries reveals significant differences between regions.

This paper examines how internal migration distance and its frictional effect vary between countries. Such comparisons are hampered by differences in the number and configuration MAUP W use the flexible aggregation routines embedded in the IMAGE Studio, a bespoke software platform which incorporates a spatial interaction model, to elucidate these scale and pattern effects in a set of countries for which finely grained origin-destination matrices are available.We identify an exponential relationship between mean migration distance and mean area size but show that the frictional effect of distance remains remarkably stable across spatial scale, except where zones have small populations and are poorly connected. This stability allows robust comparisons between countries even though zonal systems differ. We find that mean migration distances vary widely, being highest in large, low density countries and positively associated with urbanisation, HDI and GDP per capita. This suggests a positive link between development and migration distance, paralleling that between development and migration intensity. We find less variation in the beta parameter that measures distance friction but identify clear spatial divisions between more developed countries, with lower friction in larger, less dense countries undergoing rapid population growth. IntroductionMigration can be defined as changing residence from one geographical location to another.Whether this involves a permanent or a temporary relocation, travel occurs over a specific distance. As with many other forms of spatial interaction, migration conforms with the axiom following from ' proposition in the nineteenth century that (Ravenstein, 1885, p. 198). Implicit in this statement is that fewer migrants travel longer distances and that distance therefore exerts a frictional effect on migration behaviour. 3Bell et al. (2002) identified distance, along with intensity, connectivity and impact as the dimensions of internal migration that are important to consider when making crossnational comparisons. M residence, measured in the form of a rate or probability, whilst connectivity refers to the extent to which regions are linked by migration flows and can be measured using a simple index such as the proportion of the total flows between regions that are non-zero. Migration impact, on the other hand, indicates the extent to which migration transforms the pattern of population settlement and can be measured using a number of indicators such as migration effectiveness or aggregate net migration. Elsewhere we have examined the data available for making such comparisons (Bell et al., 2014b), developed software to compute comparative indicators and address key methodological issues (Stillwell et al., 2014), and assessed how countries differ with respect to overall migration intensities (Bell et al., 2015). In this paper, we turn to the distance dimension in order to examine how far people move and the frictional effect of distance on internal migration in countries around th...