Validating integration and citizenship policy indices

After a long period of mostly case study research, in the recent past various integration and citizenship policy scholars have started to compare a relatively large range of countries by constructing policy indices. As there are almost as many indices as there are such studies, one might wonder whether it matters which indices we use. The main goal of this article is to compare these indices and to investigate commonalities and differences. By means of content, convergent and construct validity tests, methodological strengths and weaknesses will be discussed. It will be shown that most of the indices consist of different components and are sometimes weakly related to each other even if they can be explained by similar factors. An overview of the current state of research in this field allows us to learn from the innovative ideas that have been developed so far and to discuss the next steps to be taken