Methods of measuring internal migration.

Abstract

Migration has been defined as spatial or geographic mobility involving a change of residence between clearly defined georgraphic and administrative areas. This study of internal migration involves several types of migratory moves: 1) rural to urban migration, 2) rural to rural migration, 3) urban to rural migration, 4) urban to urban migration, and 5) interregional migration. This paper reviews the sources of data on internal migration and discusses the methods which have been developed to measure internal migration in the attempt by social scientists to study the various aspects of the phenomenon. Internal migration information may be obtained through responses to direct migration questions in censuses and surveys or indirectly through the analysis of aspects of population data of component areas in successive censuses. The methods used in measuring internal migration are classified into 2 main types: direct and indirect methods. The direct measures are based on data from the following census topics: 1) places of birth, 2) duration of residence, 3) place of last residence, and 4) place of residence at a fixed prior date. The indirect methods of internal migration estimation are classified into 2 broad types: 1) the National Growth Rate Method, and 2) Residual Method comprising the Vital Statistics method and the Survivial Ratio method. The principle of the indirect method is that population increment between and 2 dates for any geographic area is the result of natural increase and net migration. In general, an internal migration rate is the number of internal migratory events divided by the population exposed to the possibility of internal migration. In practice, the population of a given area is used as the base for the calculation of in, out, and net migration rates for the area.