Minimising Country Biases in Patent Value Statistics: a Closer Look at Forward Citations

The use of patent statistics to map innovative performance and technological progress of industries and nations has expanded rapidly in recent years. It is now established that triadic patents, as published by the OECD, minimize home bias effects seen in patent counts for international comparisons. However, biases in qualitative patent indicators have been largely neglected. We account for this by examining the effect of home bias, self citations, and the speed of knowledge flows on forward patent citations for drug patents published by the USPTO for the period 1980-2008. The analysis shows that when we adjust for citations from non-triadic patents the home bias in citations diminishes. The results also suggest that self citations and the age distribution of citations are important factors in explaining some of the cross-country differences in pharmaceutical citations