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...

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...

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...

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....

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,...

Content providers rely on advertisers to pay for content. TiVo, remote controls, and pop-up ad blockers are examples of ad-avoidance technologies that allow consumers to view content without ads, and thereby siphon off the content without paying the ‘price.’ We examine the content...

Using a unique dataset we examine empirically which factors explain output per contributor in open source projects. We find that the output per contributor of open source programmes is much higher when licenses are less restrictive. Further examination suggests that the difference in output per...

We employ a unique data set on white-collar workers that combines direct observations of individual use of information technology as well as objective information on individual performance. The main hypothesis we examine is whether heavier users of IT are more productive, and if heavier users of...