A zero-inflated Poisson model of migration frequency

"This paper shows that the frequency of migration can be best modeled by a zero-inflated Poisson process, because it takes into account the overwhelming presence of zeros (nonmigrants) in the data. A failure to do so can cause the coefficients to be biased and also result in poor prediction. The major finding is that by using a zero-inflated process, the performance of the model in predicting migration behavior is substantially improved. In addition, frequent movers tend to be white, nonunionized, and tend to have fewer children, less stable marriages, and more frequent occupational changes." Data are for the United States for the years 1977 to 1987 and are taken from the Panel Study of Income Dynamics.     

Interregional labor migration and information flows

A model of interregional labor migration is developed that incorporates a complex system of information concerning migration and employment opportunities, as well as a heterogeneous population in which groups of workers differ in their assumed levels of skill, attitudes toward risk, and willingness to move. "Three channels are examined: interpersonal communication, general source information, and specific source information targeted at unemployed workers. In this process, trajectories of welfare levels (composed of wage plus nonwage benefits), information flows, vacancy and unemployment levels are generated for different worker and job types, regional aggregates, and the system as a whole. The behavior of the model is examined by means of numerical simulations and sensitivity analyses."     

Multiregional estimation of gross internal migration flows

"A multiregional model of gross internal migration flows is presented in this article. The interdependence of economic factors across all regions is recognized by imposing a non-stochastic adding-up constraint that requires total inmigration to equal total outmigration in each time period. An iterated system estimation technique is used to obtain asymptotically consistent and efficient parameter estimates. The model is estimated for gross migration flows among the Canadian provinces over the period 1962-86 and then is used to examine the likelihood of a wash-out effect in net migration models. The results indicate that previous approaches that use net migration equations may not always be empirically justified."     

A model of urbanization with nonlinear migration flows

"This paper seeks an appropriate specification of the migration exchange between rural and urban areas so that the implied evolution of the degree of urbanization agrees with its commonly observed S-shape. After demonstrating that the gross migration flows between rural and urban areas should be specified as nonlinear functions of the population in the origin sector, the paper introduces a model in which such flows are represented by gravity-type functional forms....[The model] can be used to give insights into the time paths of three basic urbanization variables: the urban-rural growth rate differential, the rural net outmigration rate, and the urban net immigration rate. All take on a zero value at the two extremes of the urbanization process and evolve in between according to a bell-shaped curve. These findings are illustrated by applying the model to data from the United States for the period 1790-1980."     

Modelling migration flows of immigrant groups in Canada

"In this paper, the authors briefly review the findings of an earlier study on the patterns of both regional and metropolitan redistribution of immigrant groups in Canada. Against this backdrop, a hierarchical model of migration for immigrant groups for the period 1981-86 is developed and estimated. The internal redistribution of immigrants through postarrival migration has continued to be focused on metropolitan areas in general and on Toronto, Vancouver, and Montreal in particular. The distribution of previous immigrants plays a significant role over and above that of economic circumstances both in retaining immigrants in a particular city and in attracting members of immigrant groups from other cities."     

Inferring migration flows from the migration propensities of infants: Mexico and Indonesia

The need for methods of indirectly estimating migration flows is particularly important in developing countries, where migration data are often incomplete and inaccurate. This paper focuses on the use of an indirect internal migration estimation method applied to Mexican and Indonesian census data. It shows that the mobility propensities of infants can be used to infer the corresponding propensities of all other age groups. However, the promise of this method is reduced in instances of inadequate data, and great care must be taken to identify outlying values in the data and to correct obviously erroneous patterns. Future work increasingly will be directed to this issue.     

Estimation of place-to-place migration flows from net migration totals: a minimum information approach

"A truism in demography has been that net migration may be derived from information on gross place-to-place flows, but that gross place-to-place flows cannot be inferred back from information on the net population movements in a system. Some recent work on maximum entropy and minimum information models, however, suggests a possible means for estimating just such as set of place-to-place flows. The net migration constrained model presented here could prove particularly useful for updating detailed migration matrices on the basis of current net migration estimates, and could even provide some clues as to the nature of the still poorly understood relationship between gross and net migration. Performance of the model is demonstrated using flow matrices from the 1960 and 1970 U.S. Censuses.     

自然置换通风的气流模型研究

提出一个室内上下区气流温度分别呈线性分布的模型,用该模型模拟了自然置换通风气流的温度分布,分析了分界面高度和通风量变化的影响因素,并用已有实验结果检验,经检验,两区域模型基本可以用于模拟自然置换通风室内气流在空间上的温度分布.     

Age articulation of U.S. inter-metropolitan migration flows

A fundamental divide in migration research has existed between aggregate studies of movement among geographic regions and micro studies of individual migrant behavior. Micro-scale studies have highlighted the importance of stage of life-cycle in predicting movement propensities, whereas many aggregate studies have focused on age-aggregated data summed over all origins for in-migration and over all destinations for out-migration. In this paper we show that if data for functional metropolitan-centered regions are employed, and if origin-destination specific streams of movement are analyzed, the age-specific patterns of inter-metropolitan migration within the United States cluster into distinctive patterns of flow representative of key stages of the life-course. In order to expose and portray a rich, age-articulated geography of U.S. migration we aggregate county-to-county migration flow data from the 1990 census for extended metropolitan regions: Bureau of Economic Analysis (BEA) Economic Areas. We calculate destination-specific out-migration rates broken down into 17 age groups for each origin-destination-specific migration stream between pairs of Economic Areas and present the results of a factor analysis of these flow-specific age profiles. We use the factor scores to cluster the very large number of origin-destination-specific age profiles and find that seven characteristic types emerge reflecting key mobility stages of the life course. We analyze the distinctive characteristics of the migration flows in each cluster and based on the prevalence of flows of each type within streams of gross in- and gross out-migration we present a typology of the 172 BEA Economic Areas. Our conclusion is that better understanding the age articulation of origin-destination-specific flow patterns would help advance regional science migration research. Received: January 2001/Accepted: June 2002 Earlier versions of this paper were presented at the 47^th North American Meetings of the Regional Science Association International, Chicago, Illinois, USA, November 9–12, 2000 and at the 12^th International Symposium Hosted by the Executive Secretariat of the Pacific Regional Science Conference Organization, Tokyo, Japan, October 1–3, 2000. The authors thank Joseph Persky, Roger Bolton, Hiroyuki Shibusawa, and Roger Stough for helpful suggestions made at those two presentations. The authors gratefully acknowledge the expert computer programming assistance of Lucy M. Carruthers of the Center for Computing and Information Technology of the University of Arizona. We also thank Chris Henrie, Ph.D. student, University of Arizona, for constructing our base map of BEA Economic Areas. Frank Heins would like to thank the National Research Council of Italy (Short-term Mobility Program 1999) for financially supporting a stay at the Department of Geography and Regional Development, University of Arizona. During his stay the groundwork for this research was laid. David Plane would like to acknowledge the support of the Population Division, U.S. Census Bureau for his 2001–2002 academic year visiting research position during which the final analyses and revisions were made.     

Economic-demographic models for forecasting interregional migration

"A class of spatial economic-demographic forecasting models is proposed. The models combine elements of traditional Markov and economic gravity models. A base-period probability structure is modified by the changing relative distribution of economic opportunity. Estimation issues are addressed, and an empirical application to US interstate migration during the late 1970s is described. It is contended that the framework represents a merger of past demographic and economic modeling traditions in a spatial interaction framework."     

Analysis of alternative labor-force population migration forecasting models

This study evaluates the ability of a model using economic and demographic variables to predict migration patterns. The regression model tested is based on an analysis of migration hypotheses, operationalized on a past time period, and evaluated with the method used by the Bureau of the Census. Dollar value estimates using recent Federal revenue sharing allocations are made with the alternative forecasting methods for one State in each of the Bureau of the Census regions. The results show that the model that is developed provides a firmer basis for projection confidence than does one which relies solely on trend extrapolation.The authors would like to thank Hugh Folk and Ken Cogger for several helpful comments. This paper was supported in part by a grant from the Employment and Training Administration, U. S. Department of Labor.     

Regional adjustment and migration flows in Canada, 1971 to 1981

The primary purpose of this paper is to consider and test for various interlinkages between migration flows, and also between migration and employment change. Three types of migration flows are distinguished: domestic in-migration and outmigration, and net international migration. The three migration equations are embedded in a model of regional adjustment that also includes regional employment and wage changes as endogenous variables. The data base utilizes Canadian census statistics for 1971 and 1981 in a cross-section analysis with 183 regions represented by counties, or theri equavalents. The empirical performance of the various interlinkages is broadly in line with expectations, but the results raise some important questions about interpretation.     

Interregional migration models with source and interaction information

"Information flows in models of migration are emphasized. In particular, migrants are assumed to react to two types of information about job vacancies. 'Interaction information' may be defined as interpersonal communication between recent migrants and their former neighbors or friends, and 'source information' represents a direct flow of information from employers or agencies to individuals. Models are developed that investigate the effects of various communication rates and information retention levels on vacancy rates and labor-force population trajectories. It is found that attempts by planners to reduce regional inequities in vacancy rates through controlled advertising may be successful, but at the possible cost of increasing temporal fluctuations of regional vacancy rates."     

Competing destinations and intervening opportunities interaction models of inter-city telecommunication flows

This research makes use of a large sample of individual telephone calls between local exchanges (cities, towns, villages) within a U.S. region. The interlocational flows, measured in conversation seconds, are analyzed by estimating, in a simultaneous equation framework, spatial interaction models that account for (1) the role of the spatial structure, which reflects the competition and agglomeration effects that take place among the flow destinations, and (2) the role of the reverse flows, which reflect the process of information creation necessary to complete economic and social transactions. A particular focus is set on Fotheringham's competing destinations model and Stouffer's intervening opportunities model. The implications of the results are discussed and areas for further research are outlined. Received: 1 September 1998 / Accepted: 18 December 1998     

Research policy and review 30. How to add value to migration data from the 1991 census

"The form in which migration information is likely to be provided from the 1991 Census [of the United Kingdom] is reviewed, and suggestions are made about how this provision can be improved for the academic research community, building on the experience of the 1981 Census. The recommendations add considerable value to the information at relatively low cost."     

饱和正冻土中水热迁移的热力学模型(英文)

应用连续介质的混合物理论研究了饱和正冻土中的水热迁移问题。主要结果有：①提出了正冻土中层冰形成的一个判别法则；②将水热迁移问题化为含可动边界的非线性Ｂｕｒｇｅｒｓ方程，为研究冻土水热迁移的非线性效应提供了一个理论上的出发点。