## 3 Materials and Methods  
### Document Collection  
The U.S. Patent & Trademark Office (PTO) makes the full files of post-grant review decisions available online at the PTAB Open Data website, [[https://developer.uspto.gov/ptab-web/#/search/decisions](https://developer.uspto.gov/ptab-web/#/search/decisions)]([https://developer.uspto.gov/ptab-web/#/search/decisions](https://developer.uspto.gov/ptab-web/#/search/decisions)), accessed on 3 April 2022 (additional options are available to search for proceeding records and documents). Data are available for download via a PTAB API ([[https://developer.uspto.gov/api-catalog/ptab-api-v2](https://developer.uspto.gov/api-catalog/ptab-api-v2)]([https://developer.uspto.gov/api-catalog/ptab-api-v2](https://developer.uspto.gov/api-catalog/ptab-api-v2)), accessed on 3 April 2022), and there are additional bulk download options for patent text and subject matter codes. For this paper, information is accessed and documents downloaded through this API for all AIA post-grant review (CBM, IPR, and PGR) proceedings from the inception of the programs on 16 September 2012 through 31 December 2021. Manual inspection and the Docket Navigator database ([[http://www.docketnavigator.com](http://www.docketnavigator.com)]([http://www.docketnavigator.com](http://www.docketnavigator.com)), accessed on 3 April 2022) are used to identify proceedings in which an institution decision was reached, excluding proceedings in which a party joined a petition filed by another party and proceedings that terminated prior to an institution decision, which usually occurs either because the patent owner disclaimed the patent or the parties reached a settlement. We identified 11,047 proceedings that met these criteria.  
The PTAB API can then be used to download petitions, preliminary response briefs, and written institution decisions using the identified proceeding numbers. While the API allows for the download of documents by type, we found that this was often unreliable, because types are recorded inconsistently in the system. For example, a preliminary response brief (POPR) should be identified as a preliminary response, but it is sometimes identified as a response, which then can create confusion with responses to procedural motions or the post-institution response brief. Similarly, institution decisions may be filed under a number of different document types. Accordingly, a variety of keywords in the \"documentTypeName\" and \"documentTitleText\" fields are used to download the correct document. The PDF files are then downloaded and converted to text using pdfplumber ([[https://github.com/jsvine/pdfplumber](https://github.com/jsvine/pdfplumber)]([https://github.com/jsvine/pdfplumber](https://github.com/jsvine/pdfplumber)), accessed on 3 April 2022). The script used to obtain this paper's results is available at our Github, [[https://github.com/EESI/PTAB](https://github.com/EESI/PTAB)]([https://github.com/EESI/PTAB](https://github.com/EESI/PTAB)) (accessed on 3 April 2022).  
When preparing the data for this paper, not all documents could be downloaded. In many instances, this was because documents for certain proceedings were simply unavailable through the PTO's Open Data system due to technical issues and unreliability of the database. Additionally, some documents generated errors due to corrupted PDF files or errors in the PDF download and conversion to text processes that persisted even after repeated attempts. Ultimately, we downloaded documents for 10,462 cases; although, in some cases these included errors or a case may have only included one or two of the three types of documents. In sum, our dataset, which is made available on our Github, includes 9079 cases with written decisions, 10,060 cases with petitions, and 9283 cases with preliminary responses (although we have made the full data set available, petitions were not analyzed in this study).