Patent Office Citation Practices
Citation Differences Between Technology Fields
Introduction
The Technology Relevance is an indicator of the technological importance of the patent family. It is calculated on the patent family level based on the number of subsequent art citations (forward citations) the patent family has received. The number of citations received by the patent family is adjusted by three factors: the patent office citation practices, the age of the patent family, and the technology fields to which the patent family belongs.
The Technology Relevance measures the significance of a patent family (invention) for further technological development. It is calculated based on the number of worldwide prior art citations the patent family has received from other patent families. In numerous scientific studies, this metric has been found to be a valid indicator of the relevance of the invention.
Citation-based indicators are also used with great success in other domains: The Google search engine uses citations between web pages to estimate the relevance of these pages. Scientists evaluate the impact of their research based on the number of citations they receive.
Patent prior art citations made primarily by patent examiners from around the world are considered to compile an unbiased view of the overall worldwide impact of an invention on further technological development. The Technology Relevance is calculated based on prior art citations from all patent offices contained within our database including USPTO, EPO, WIPO, SIPO, JPO, and many others. PatentSight also considers citations made by the applicants (applicant citations), which account for roughly 15% of all citations in the database.
The number of patent citations received by a given family is divided by the average number of citations received by "similar" families, defined by the following three factors:
Patent Office Citation Practices
Citation practices can differ from patent office to patent office. The USPTO, for example, cites on average significantly more than other patent offices. To take such differences into account, a citation from a patent office that, on average, makes fewer citations is weighted higher than a citation from a patent office that, on average, makes more citations.
Moreover, if a patent family is cited by more than one member of another patent family, the citation that is weighted the highest is used for the calculation of the Technology Relevance.
For more details, see also What is Family to Family Citation?
Age of the Patent Family
On average, older patent families tend to have received more citations than patent families that have only recently been published. This is simply due to having been publicly available for a longer period of time.
To correct for the age of a patent family, the number of citations received by the patent family is divided by the average number of citations received by all patent families that have been first published in the same year.
Citation Differences Between Technology Fields
The average number of citations can also significantly differ depending on the technology field. For example, patent families from the field of mining technologies might, on average, receive fewer citations than patent families from the field of heterocyclic compounds.
The number of citations a patent family has received is divided by the average number of citations received by all patent families in same the technology field. The 4-digit IPC subclasses (e.g., "H01L") are used to assign patent families to technology fields.
Consequently, the Technology Relevance can be defined as a relative measure that compares a patent family to other patent families. For example, a Technology Relevance of "2" means that a patent family has been twice as relevant for further technological development as an average patent family in the same technology field and of the same age.