In many datasets, articles are classified into sub-fields through the journals in which they have been published. The problem is that many journals are assigned to a single sub-field, but many others are assigned to several sub-fields. This paper discusses a multiplicative and a fractional...

This paper evaluates the European Paradox according to which Europe plays a leading world role in terms of scientific excellence, measured in terms of the number of publications, but lacks the entrepreneurial capacity of the U.S. to transform this excellent performance into innovation, growth,...

The paper is devoted to an econometric analysis of learning foreign languages in all parts of the world. Our sample covers 193 countries and 13 important languages. Four factors significantly explain learning, two of which affect the broad decision to learn, while two concern as well the choice...

This paper studies evidence from Thomson Scientific about the citation process of 3.7 million articles published in the period 1998-2002 in 219 Web of Science categories, or sub-fields. Reference and citation distributions have very different characteristics across sub-fields. However, when...

This paper investigates the citation impact of three large geographical areas -- the U.S., the European Union (EU), and the rest of the world (RW) -- at different aggregation levels. The difficulty is that 42% of the 3.6 million articles in our Thomson Scientific dataset are assigned to several...

This paper uses high- and low-impact citation indicators for the evaluation of the citation performance of research units at different aggregate levels. To solve the problem of the assignment of individual articles to multiple sub-fields, it follows a multiplicative strategy according to which...

We study a number of mechanisms through which an economy can be stuck at a high unemployment equilibrium because a poor labour market is associated with support for poor policy. These mechanisms are consistent with the relative scarcity of measures that have been undertaken to cure unemployment....

This paper summarizes the study design of the Rural–Urban Migration in China and Indonesia (RUMiCI) project. We first discuss the overall distribution of migrants in Indonesia and the selection of survey cities. Next, we describe the process of identifying the migration status of each...

The use of payment cards, either debit or credit, is becoming more and more widespread in developed economies. Nevertheless, the use of cash remains significant. We hypothesize that the lack of card acceptance at the point of sale is a key reason why cash continues to play an important role. We...

We consider a pure exchange economy, where for each good several trading institutions are available, only one of which is market-clearing. The other feasible trading institutions lead to rationing. To learn on which trading institutions to coordinate, traders follow behavioural rules of thumb...