Industry Classification of Patent Data
Patent data are usually classified by functional use instead of industry of use or industry of manufacturing. For example, a fishing reel and a bobin are both classified under U.S. Patent Class 242: Winding, Tension, or Guiding. This makes it difficult to link patent data to other data that are classified by Standard Industrial Classification (SIC).
The most correct solution to this is to manually classify the patent in question into the SIC by reading through the patent grant document that specifies the invention in details. However, this is an insurmountable task. Alternatively, (for contemporary patent data) we can utilize a patent-industry concordance system that assigns a probability associated with each patent class and each industry class, and maps a patent count for each patent class into a patent count for each industry class. For example, if a probability that a patent awarded in class A is made by industry B is 0.2 and if there are 100 patents awarded in class A, then such a concordance system will yield 20 patents made by industry B.
There are two patent-industry concordance systems that convert International Patent Classification (IPC) into SIC:
- Yale Technology Concordance (YTC)
- Silverman’s International Patent Classification-U.S. SIC Concordance
In addition to the two patent-concordance systems discussed above, sometimes we may need to perform another conversion before being able to utilize these concordance systems. For example, patents granted by USPTO are mainly classified according to the U.S. Patent Classification (USPC). Therefore, we will need Wellesley Technology Concordance (WTC) that converts USPC to IPC before using either YTC or Silverman's Concordance.