Differences in citation impact across countries

Using a large dataset, indexed by Thomson Reuters, consisting of 4.4 million articles published in 1998-2003 with a five-year citation window for each year, this paper studies country citation distributions in a partition of the world into 36 countries and two geographical areas in the all-sciences case and eight broad scientific fields. The key findings are the following two. Firstly, the shape of country citation distributions is highly skewed and very similar to each other across all fields. Secondly, differences in country citation distributions appear to have a strong scale factor component. The implication is that, in spite of the skewness of citation distributions, international comparisons of citation impact in terms of country mean citations capture well such scale factors. The empirical scenario described in the paper helps understanding why, in each field and the all-sciences case, the country rankings according to (i) mean citations and (ii) the percentage of articles in each country belonging to the set formed by the 10% of the more highly cited papers are so similar to each other.