The assumption of equilibrium in the analysis of migration and interregional differences: a review of some recent research

"This paper questions the plausibility of the assumption of interregional equilibrium in recent research into migration and the valuation of amenities in the United States. It is shown that it is difficult to develop a satisfactory explanation for continuing net migration which is compatible with the equilibrium assumption, and that recent relevant research generally fails to support the idea that the U.S. economy is in equilibrium. The association of higher rent levels with in-migration is explained as a short-run phenomenon. If the spatial economy is in disequilibrium, then the valuations of amenities assuming equilibrium will be biased, being probably too low in areas of net in-migration and too high in areas of net out-migration."     

An equilibrium model of gross migration

ABSTRACT The paper presents and tests a new model of migration which differs significantly from the conventional disequilibrium approach. We show that variations in rates of gross migration across regions are equilibrium responses to variations in levels of amenities, governmental policies, etc. The model is tested using data on the gross migration of whites, 1975-80, together with amenities such as climate and with economic variables such as government services, taxes and unionization. Empirical results suggest that the equilibrium model is more consistent with actual migration patterns than is the conventional disequilibrium approach. We estimate compensating differentials and migration elasticities for these variables.     

The direction of migration: a dynamic general equilibrium model

A two-sector dynamic general equilibrium model is developed "to investigate the direction of migration in response to differing demographic and consumption demand behavior, as well as variations in production conditions." The model, which involves a rural sector and an urban sector, incorporates "returns to scale and the natural rate of sectoral population growth as important determinants of the direction of migration, in addition to price and income elasticities, and the sectoral technical change rate with which...previous studies dealt."     

Serial correlation in multiregional migration models

"In this paper, we outline the specification and estimation of a time series of multiregional net-migration equations subject to first-order serial correlation. We show that the necessary nonstochastic adding-up constraint, which requires that net migration in the system sum to zero, imposes restrictions on the serial-correlation coefficients. We estimate equations under these restrictions using data for the ten Canadian provinces for the period 1962-1985. The results confirm the significance of the serial-correlation coefficient and, hence, the importance of incorporating this correction in future time-series models of multiregional migration."     

Time-series modeling of gross migration and dynamic equilibrium

Firstly, the high association between in- and out-migration is investigated in a time-series context and modeled according to three categories: 1) job transfer, 2) job search and marriage, and 3) return migration. Under certain coditions it is shown that aggregation of these migrations yields a bivariate time-series model having feedbacks in both directions. Secondly, the recent phenomenon of sharp changes in net migration seems to be discontinuous and, hence, catastrophic modeling [Casetti (1981) may be appropriate. However, this paper considers gross migration between cores (metropolitan areas) and peripheries (rest of the nation) for which a continuous function seems adequate. This is done by introducing a multivariate time-series model. This model is empirically supported, especially in Japan, divided into 32 regions, by t-tests and Durbin-Watson ratios, although it excludes economic variables such as employment growth and wage differentials. This may imply that the recent dispersal from core to peripheral regions could be explained primarily by feedback from return migrants. Finallym, provided future streams of gross migration follow the past trends given by simultaneous equation estimates, in-migration and out-migration would approach a stable state in most regions. Irrespective of random shocks in the future, in- and out-migration would tend to approach a stable equilibrium. According to the estimation of the stable states, the 45 core regions in the US would continue to lose population through net outflows while those in Japan would continue to gain. The present model may thus be valid only for short-term forecasts. By introducing feedback and lag structures, however, it does offer one explanation for the recent population turnaround.     

A general equilibrium analysis of rural-urban migration under uncertainty

ABSTRACT. This paper analyzes the implications of an exogenous shift in relative prices for an economy that suffers from urban unemployment, as well as uncertainty, in the agricultural sector. Among other things, we show that with agricultural uncertainty, an exogenous shift in relative prices will lower agricultural profit. This result is in sharp contrast with the conventional case of risk-neutrality or certainty where agricultural profit is unaffected by changes in the terms of trade.     

Incorporating the effects of spatial structure in discrete choice models of migration

Discrete-choice theory and logit models are evaluated for their usefulness in analyzing migration patterns in a zonal system. The authors "argue that spatial effects and more specifically the relative location of zones are not taken into account in such analyses. We, therefore, introduce a measure of spatial structure and advocate its usage as a predictor of migration in such models. In an example of intrametropolitan migration in Toronto [Canada], we demonstrate that this variable is not only significant but also it improves the performance of all the other variables with the greatest impact on the distance between zones. In addition, inclusion of this variable improves the overall performance of the model in terms of residuals."     

A note on specification of climate variables in models of population migration

"In the literature on population migration, increasing attention has been devoted to quality-of-life factors. Measures of temperature (as proxies for climate) have frequently been employed in empirical work regarding the determinants of population migration decisions. A wide range of such specifications have been used, most of which imply restrictions on the preferences of migrants. In this paper, a variety of temperature variable specifications are analyzed and interpreted. Statistical tests for nested and nonnested hypotheses are used to compare and choose among the various specifications." The model is used to analyze interstate migration in the 48 contiguous states of the United States for the period 1975-1980.     

On the role of amenities in models of migration and regional development

"The role of location-specific amenities in human migration decisions, and subsequently regional development, is explored. A framework is developed which motivates a new assessment of existing alternative models of regional development, indicating the need for additional modeling efforts which focus upon amenities as critical elements in such analyses. The approach hinges upon the notion that amenity values are capitalized into wages, rents, or other local prices. This process of capitalization enables researchers to explore the implicit value that society places upon amenities, which can then be used in assessing future regional-development trends in a more comprehensive manner."     

Numerical models of petroleum migration via buoyancy-driven porosity waves in viscously deformable sediments

The apparent ability of petroleum to migrate rapidly through low permeability sediments in sedimentary basins has led to many questions about the manner of its transport. One possible explanation is suggested from observations of the compaction of viscously deformable porous media. These systems have been found in some cases to give rise to regions of locally elevated liquid fraction, in the form of fluid‐filled porosity waves that can ascend at rates much greater than that of the background flow. Previous research on the phenomenon has focused on its implications for magma transport, but recognition of the fact that the compaction of viscous porous media can take place in sedimentary basins has suggested the possibility that porosity waves could similarly be important for hydrocarbon transport. The purpose of the present study was to test this hypothesis by quantifying the transport that would occur as the result of porosity waves initiated during the conversion of kerogen to petroleum. A one‐dimensional numerical model was constructed solving equations for the mechanics of viscous compaction and for the kinetics of reactions describing the formation of petroleum from kerogen. The results showed that porosity waves would develop readily in viscously deformable regions of sedimentary basins, but would not necessarily provide enhanced transport over that of the background flow regime. In order for the waves to achieve this enhanced transport, they must develop high amplitudes, i.e. high porosities relative to the background porous medium. To achieve the high wave amplitudes, the background porosity must be very low in absolute terms. In addition, high kerogen contents are needed in the source layer, and the source layer needs to be buried rapidly to a high temperature region of the oil window. Considerable uncertainty exists as to the value of the matrix shear viscosity of sediments in basins. However, the wave volumetric transport capacity was not found to be significantly altered as a result of variations in the value of this parameter. The physical form of the waves was strongly altered by the matrix shear viscosity, with higher values leading to lower amplitudes and generation frequency, but higher wavelengths. Thus the waves become less recognizable physically at higher values of the matrix shear viscosity. As the waves ascend to higher stratigraphic levels, where the porosity is higher, they gradually lose their physical definition and become absorbed into the background.     

Human migration: theory,models, and empirical studies

A general review of studies on internal migration within the United States since 1970 is presented. The author first describes the changes that have occurred during the recent past in U.S. internal migration patterns. The state of knowledge concerning these changes is also assessed. A more abstract discussion of the determinants of migration, covering both the theoretical and empirical literature, is then presented. Next, the empirical findings associated with several new time-series migration data sets are reviewed, and the application of econometric methodologies to temporal models of migration is considered. The review concludes with a summary of recent research results and some pointers for future research.     

中国古代人际传播思想中的关系假设

人际传播是人与人之间的意义创造和意义关系的交流.它因人们的交往关系而存在并运用于交往关系之中.关系总是同传播紧密地联系在一起而不可分割的.中国传统文化中关系假设无所不在.正是这些建立在通常假设意义的核心基础之上的"关系"理论造成中国古代乃至现代华人社会信息传播的隐蔽性.因此,只有研究维系中国古代人际传播秩序的关系假设,才能正确诠释"仁"、"礼"、"忠恕"、"和为贵"等传统思想范畴在古代人际传播过程中的意义.     

The determinants of labor migration in Egypt

The factors which affect individual decisions with regard to geographic movement in Egypt are examined and the magnitude in which each factor exerts its influence on aggregate geographic labor supply adjustments is estimated. The spatial unit used in the study is the administrative region, of which there are 25. No effort is made to esimate the impact which migration has had on the origin or destination region. The migrant will presumably choose that destination which, given his information, the migrant thinks will be best. The model which is employed attempts to explain gross interregional migration without the explicit introduction of an individual decision function. Rather, migration is related to certain aggregate proxy variables. Among the independent variables employed in the analysis are (origin and destination) income, education, urbanization, and population. The other explanatory variable used is the distance between region i and region j. The migration measure employed refers to cumulative male migration which occurred prior to 1960; the independent variables are defined for a given point in time (1960). The independent variables explain a reasonably large percentage of the variance in migration between regions in Egypt. All variables were significant at the 5% level or better. The findings indicate that distance acts as an important impediment to migration. Migration is away from low wage and toward high wage regions, which may have contributed to a narrowing of regional wage differentials. Migrants are attracted to regions which have large populations and to regions which have a large percentage of urban to total population. A tendency exists for migrants to come from regions with large populations. There is also some tendency for migrants to come from regions which have a relatively large urban population. Migrants do not appear to come from regions with high educational levels.     

Stable state conditions of population-dependent migration models under a zero natural growth rate

The author "attempts to examine the stable conditions of regional population under a zero natural growth rate in the context of a certain general class of [population-dependent] nonlinear migration models." Theorems regarding the stable state conditions of the migration models are presented. The parameters of the gravity migration model are then estimated empirically using data on Japanese inter-prefectural migration flows in 1966, 1970, and 1975. The possibility of achieving the stable state in Japan is discussed     

The specifics and spatial structure of circular migration in Russia

Abstract

This article aims at distinguishing recurrent population movements within the territory of the Russian Federation between urban localities of different sizes and rural areas in connection to the processes of urbanization, suburbanization, and de-urbanization. Incomplete urbanization and the strong polarization of socio-economic space in Russia have resulted in two powerful contradictory population flows: centrifugal seasonal sub- and de-urbanization and centripetal labor migration from rural and small towns to large urban centers. The article discusses three forms of recurrent population mobility in Russia: (1) daily commuting of urban and rural inhabitants within metropolitan areas; (2) commuting to large cities and their suburbs for long-term employment intervals (weekly, monthly, etc.), (3) second-home commuting to countryside dachas. Unfinished urbanization in Russia not only attracts rural and small towns’ population to major cities but also keeps it within the latter. It slows down the real de-urbanization and induces specific dachas (second-home) suburbanization/de-urbanization, with these processes being closely interrelated. An opportunity to earn money in cities together with the impossibility of moving to major centers due to expensive housing encourages households to remain in small towns and rural areas. Meanwhile, inhabited rural localities (even ones distant from cities) attract seasonal population (dachniks).     

Ecological equilibrium and territorial planning: The Italian case

The purpose of this paper is to illustrate briefly (a) the scientific premises of territorial planning, which are also the foundations of an ecological equilibrium between human activities and the territory or natural environment; (b) the lines of direction of an urban policy inspired by the above‐mentioned foundations of ecological equilibrium; and then subsequently (c) the guidelines for the application of the principles of ecological‐territorial equilibrium in Italy; with the subsequent configuration of (d) an urban eco‐systems network for Italy (as designed by the ten‐year plan for the environment, elaborated last year by the Italian government).     

The effects on earnings of interregional and interindustry migration

"The purpose of this study is to examine a model of the decision to migrate between regions and/or industries and its effect on earnings. The study is based on a large set of individual microdata taken from the [U.S.] Social Security Administration's One Percent Continuous Work History Sample." The data are for 1971 and 1973. "Results of estimation provide strong support for the hypothesis of self-selection among region and industry migrants. Additional empirical evidence supports the notion of comparative advantage in migrant earnings, implying that earnings distributions of individuals who made a particular combination of migration decisions may differ from those of the population as a whole."     

The context of migration: the example of Ireland in the nineteenth century

"A classic case where out-migration interacted with many other geographical phenomena is provided by rural Ireland in the nineteenth century. The apparent turning point was the Great Famine of the 1840s, but the areas with the greatest suffering from starvation did not necessarily show the greatest population decline, suggesting that other forces were active. Considerable economic and social changes were already taking place before the Famine: fertility was being reduced, later marriage was becoming established and considerable emigration was already taking place. Immediately after the Famine those areas which had been hardest hit often reverted to pre-Famine conditions and did not show strong population decline until the 1870s. The Famine was a most serious event, but the modernization of Irish rural life, which linked emigration with changes in family structure, agriculture and population numbers, was more important in bringing about geographical change."