Do citation counts overstate Chinese science because researchers favor home-country work?
Core argument: China shows a home bias in scientific citations of 42.3%, a clear outlier above the next-highest countries, Iran and India, each at 23.2%.
We investigate the phenomenon of home bias in scientific citations, where researchers disproportionately cite work from their own country. We measure home bias as deviations from a benchmark model, which we base on a “dartboard approach” by asking: How many citations would we expect country i to receive from country j, if world citations were distributed only according to the size of the citing and cited countries? The benchmark citation flows distribute world citations according to the total share of citations the cited country i received from the world, and the share of the size of the potential citing country j based on its world publication share. We now define home bias of a country i as the deviation of its actual citation shares from the benchmark citation share. In Figure 2 we calculate the home bias across countries implied by [this method]. All countries in our sample exhibit home bias to some extent. However, China is a clear outlier with a home bias of 42.3%, followed by Iran (23.2%), and India (23.2%). The home bias of the US is on the larger side of the remaining countries, at 15.9%.





