I was analyzing a dataset that maps US Patent Classification (USPC) subclasses to Standard Industrial Classification (SIC) codes and product fields (description here, data available here, see zip file).
However, I found that the most common SIC class to which USPC subclasses were mapped was SIC code 21 (i.e. the US Postal Service!) Why is this? This seems surprising as I do not intuitvely regard the USPS as the most innovative industry in the US economy.
Some of my theories for why this is includes:
- There may be peculiarities related to how government-owned patents are assigned SIC codes, since USPS is a government agency. This could inflate counts.
- There may be subclasses related to generic business logistics/tracking that got assigned to USPS but are more broadly applicable.
- The data is only looking at government-owned patents. So these are patents assigned to federal government agencies, not private companies. As a major government agency, it makes sense that the USPS would have a sizable patent portfolio.
- Maybe I misunderstand the nature of this data, and it might just be looking at government-owned patents. Of US government agencies, the USPS might indeed file the most patents