基于空间自相关的中国省际人口迁移模式与机制分析

人口迁移具有空间指向性,表现为迁入地和迁出地在地域上呈现一定的空间集聚特征。然而,大部分针对我国人口迁移进行分析和建模的研究忽视了这一空间指向性及其影响。该文利用全国第五次人口普查省际人口迁移数据和相关资料,以空间自相关分析为基础,对1995-2000年我国省际人口迁移的空间模式与动力机制进行了初步分析。首先,运用全局空间自相关统计量(Moran′s I)对人口迁移流中的空间自相关程度进行了测度,发现研究期间我国省际人口迁移的空间指向性明显:从一个区域出发(或抵达一个区域)的人口迁移流均受到周边地区人口迁移的影响。为了进一步研究这种空间指向性对人口迁移规模的影响,分别采用重力模型(仅用距离变量捕捉人口迁移过程中的距离衰减效应)和空间OD模型(采用因变量空间滞后的不同形式对迁移流的空间指向性加以考虑)研究中国省际人口迁移的动力机制,对比两种模型的估计结果发现:1)空间OD模型在参数估计和模型拟合等方面均优于传统的重力模型;在选取相同解释变量的情况下,空间OD模型的残差平方和仅为传统重力模型的47%,模型拟合指标AIC值也大大缩小。2)在对中国人口迁移动力机制的定量分析中,如果不考虑人口迁移流之间的空间自相关(空间指向性)现象,会导致对社会、经济等变量作用和距离衰减效应的过高估计。

Spatial Analysis of the Patterns and Mechanism of Inter-provincial Migration Flows in China

Migration flows exhibit some spatial patterns in the origin and destination places.By employing inter-provincial migration data from 2000 National Census and some social and economic data in Chinese Statistical Yearbook,the authors attempt to explore the spatial patterns of inter-provincial migration flows between 1995 and 2000 and explain the mechanisms behind the observed patterns.Firstly,global spatial autocorrelation statistics of Moran′s I is used to investigate the spatial autocorrelation in the origin and destination places.The spatial autocorrelation analysis of outmigration flow from some specified province is conducted and iterated one by one at the provincial level.Except the central provinces of Sichuan,Chongqing,Hubei,Shaanxi,Henan and Xinjiang Uygur Autonomous Region,all other provinces have positive estimated Moran′s I values.Similarly,the estimated Moran′s I values of immigration flows to all provinces are positive,which means that distance does have decay effects in the process of population migration.Then,the traditional Gravity and Spatial OD models are constructed to characterize the spatial spillover effects among migration flows and a comparison is made between the traditional Gravity and Spatial OD models.The empirical results indicate that:1) The distance decay effect in Gravity model is statistically significant at the significance level of 1%;population,FDI and education level in the destination places have expected positive sign in the estimated model and are statistically significant at the significance level of 1%;population,landuse,sex rate in the origin places do have expected positive sign and are statistically significant at the same significance level.2) Based on the spatial analysis of outmigration and immigration flows,the Spatial OD model of lagged dependent variables is constructed to fit the spatial interaction among migration flows.In comparison with the traditional Gravity model,the goodness-of-fit of the Spatial OD model is much better,which has smaller AIC value.At the same time,the estimated parameters of origin and destination places are also smaller than those of traditional Gravity model,which indicates that the influences of origin and destination places may be exaggerated in the traditional analysis.In this paper,while the spatial dependence of migration flow is modeled by spatial lagged dependent variable,further research is needed to investigate the specification of spatial lagged independent and spatial autoregressive error models.