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      What is Family-to-Family Citation?

      Last updated: June 2021

      Introduction

      How the Family-to-Family Citation Approach Influences the Counting of Citations

      How the Family-to-Family Citation Approach Influences the Calculation of the Technology Relevance

       

      Introduction

      Since the smallest unit of analysis available in the PatentSight BI are patent families, we aggregate citations on patent family level. This means that we consider citations between patent families and not between single documents.

      The reason for this approach is that, according to our patent family definition,  one patent family is, in principle, protecting one invention. Hence, this approach takes into consideration whether or not one invention is citing another invention.

       

      How the Family-to-Family Citation Approach Influences the Counting of Citations

      A patent family A with member documents in the US, DE, GB and CN is cited by a patent family B with member documents in the US, CN, and BR. In this example, two different member documents of patent family B are citing three different member documents of patent family A:

      • The US member of patent family B is citing the US member and the GB member of patent family A.
      • The CN member of patent family B is citing the CN member of patent family A.

      However, due to the aggregation of citations on patent family level,  instead of considering these citations separately as three independent citations, we count one citation between patent family A and patent family B.


      The family-to-family citation approach is significant for the following filter elements and measures:

      • Number of citations made
      • Number of citations received
      • Average number of citations made
      • Average number of citations received
      • Total number of citations made
      • Total number of citations received

      For example, if patent family A is only cited by patent family B and no other patent family, this means that the number of citations received by patent family A is "1" (and not "3").

      If patent family B is only citing patent family A and no other patent family, this means that the number of citations made by patent family B is also "1" (and not "2" or "3"). 

      How the Family-to-Family Citation Approach Influences the Calculation of the Technology Relevance

      Among other adjustments, the → Technology Relevance is adjusted for the citation practice of the citing patent office. Therefore, the family-to-family citation approach is also relevant for the calculation of the Technology Relevance and its derivative indicators. 
      In this example, patent family A receives one citation from the CN member of patent family B and two citations from the US member of patent family B. Thus, the following question may arise: Which citation, the one from the US member or the one from the CN member of patent family B,  is considered for the calculation of the Technology Relevance of patent family A?

       
      When calculating the Technology Relevance, we weight the citations a patent family has received according to the citing patent office’s citation practice. In this, we assume that a citation from a patent office that, on average, makes less citations is more relevant than a citation from a patent office that, on average, makes more citations. (Since the patent office’s citation practices may change over time, the weighting is done separately for each publication year.)
      If a patent family has received more than one citation from another patent family, we take the one with the higher weighting for the calculation of the Technology Relevance. In other words, if a patent family is cited by more than one member document of another patent family, we calculate the Technology Relevance based on the citation from the patent office that, on average, cites less prior art.
      For example, the CNIPA cites, on average, less prior art than the USPTO – in case of US documents, IDSs submitted by the applicants also have an impact. Therefore, we consider a citation from a CN document as more “relevant” and weight it higher than a citation from a US document. Consequently, in this example, we would calculate the Technology Relevance of patent family A based on the citation that comes from the CN member of patent family B and ignore the citation(s) from the US member.
       

      Important:
      For the calculation of the Technology Relevance of patent family A, it is irrelevant which or how many member documents (US, DE, GB or CN) of patent family A have been cited – we only take into consideration the patent offices where the citations come from and select the one with the highest weighting.

       

      Note that the document considered for the calculation of the Technology Relevance may change over time. Example:

      • Until 2020, patent family A was only cited by the US member of patent family B. Therefore, for the Reporting Date 12/31/2019, the Technology Relevance of patent family A is calculated based on the citation received from the US document.
      • In 2020,  patent family A was also cited by the newly published CN member of patent family B. Consequently, for the Reporting Dates 12/31/2020 and later, the Technology Relevance of patent family A is calculated based on the citation received from the CN document.
        Note that, in retrospective, this does not affect the calculation of the calculation of the Technology Relevance for the Reporting Date 12/31/2019.

      Reporting Date: 12/31/2019

      Reporting Date: 12/31/2020