Conceptual framework and data collection in international migration

The first section of this chapter focuses on an overview of the problem in measuring international migratiobn. We will recall the principal definitions used at the international level while distinguishing between data of flow and data of stock. In a second section, we will study, separately for flow and for stock, the issue of identification of the major categories of migrants and of immigrant populations. In the third section, dealing with data collection modalities, we have chosen, for practical reasons, to work according to the sources of statistics rather than the type of data. We will therefore successively study censuses, population and foreigners registers, statistics of border movements, other administrative sources and finally, specific surveys. Specific flows, like that of the movement of refugees or that of migrant workers, have not been isolated as such, for most of the general remarks apply also to these particular cases.