@article{48036,
      author = {Schwall, Aaron, and Wagner, Jeffrey,},
      url = {http://tind.wipo.int/record/48036},
      title = {The persistence of worthless patents? /},
      abstract = {The U.S. patent system requires owners to pay renewal fees  at the four, eight, and twelve-year points of the patent's  life of twenty years. Previous studies of renewal rates for  patents granted over 1981–1991 and 2001–2004 show only  around half of the patents were renewed by the twelfth  year—leading some scholars to refer to this majority of  patents as ‘worthless’. Much has changed in the world  since patent renewal fees began in 1981, however. This  paper investigates whether patent renewal rates changed  correspondingly. Among those changes, the sheer volume of  patents increased substantially, creating a challenge for  collating patent data. A web scraper was coded to collect  renewal rate data on 2.5 million utility patents issued  from 1992 to 2009—the most recent patents for which  twelve-year renewal rates are available. We find, somewhat  surprisingly, that patent renewal rates are virtually  unchanged from several years ago. We present and discuss  related data, and present the underlying computer code that  patent researchers may find useful for investigating a wide  range of topics in the future.},
      doi = {https://doi.org/10.1016/j.wpi.2023.102179},
      recid = {48036},
      pages = {1 volume.},
}