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.
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