Evaluating inventive activity: the cost of nineteenth‐century UK patents and the fallibility of renewal data

It has long been recognized that counting patents offers a poor gauge of the extent and value of inventive activity, not least because the quality of patented inventions varies enormously. The Schankerman-Pakes model provides a valuable alternative gauge that utilizes the data from renewal fees which are regularly paid to keep a patent in force. This article suggests, however, that the model’s application to nineteenth-century UK patents may underestimate the value of Victorian inventive activity because many patentees lacked the financial resources to implement the rational choice that the model assumes. Focusing on steam-engineering patents, it explores further problems with renewal data and the increasing rate of lapsed applications.