A probabilistic framework for harmonisation of migration statistics.

ABSTRACT Inadequate and inconsistent data are a common and persistent problem in the field of migration. Deficiencies in migration statistics may be tackled using modelling techniques, which has recently been recognised by the European Union (EU) policymakers. The new Regulation on Community statistics on international migration, which obliges countries to supply harmonised statistics, provides for the possibility of using estimation methods to adapt statistics based on national definitions to comply with the required 1-year duration of stay definition. The main objective of this paper is to provide a theoretical probabilistic framework to capture various migration flow statistics that are available. It is a crucial step towards better understanding and then harmonising the data. Different migration measures represent the same continuous data-generating process. They differ depending on how the data happened to be collected and how the statistics happened to be produced. We introduce the key concepts of migration statistics using a simple duration model, namely an exponential distribution. While more complex models can better reflect the reality, they do not fundamentally modify the framework presented. The main focus is put on the time criterion used in the migration definition. It refers to the duration of stay following relocation, which is specified very differently among countries and constitutes the main source of discrepancies in operationalisation of the migration concept in the EU member states. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]