Measuring irregular migrants in the informal economy

Public discussion on irregular migration frequently highlights the participation of irregular migrants in the informal economy. However, conceptual and methodological issues within two research domains-economic informality and migrant irregularity-beset the systematic study of this subject. Both phenomena suffer from competing definitions and are difficult to capture statistically, making the accurate assessment of their intersection doubly challenging. In this paper, we address the ambiguities and challenges in question. We introduce a conceptual framework that explains the differences between the informal and formal economy, unregistered vs registered firms, and irregular vs regular migration and the interactions between these concepts. We then use that framework to propose a methodological approach that relies on nationally representative survey data to estimate size ranges for populations of irregular migrant workers. We illustrate the flexibility of our method by applying it to the UK and Turkey.