{'fraction_non_alphanumeric': 0.0148861646234676, 'fraction_numerical': 0.0, 'mean_word_length': 5.28021978021978, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Historical Patent Data: A Primer and Some Pitfalls

I provide a primer on several recent historical patent datasets for use in innovation research. By comparing across these datasets, I am also able to document how the structure of raw patent data used and choices researchers made when constructing these datasets affect the conclusions drawn about the nature of U.S. invention; these same issues are likely also relevant in interpreting data on contemporary patenting. I discuss five historical patent datasets in depth, describing the strengths and weaknesses of each, the types of patent information each includes, and the contexts in which each is suitable for innovation research. While the datasets all paint a remarkably consistent picture of aggregate U.S. patenting, in many cases they consist of different patents. Differences in the underlying raw data and different techniques to ascertain invention information produce statistically significant differences in estimates of the geographic agglomeration of invention. I discuss ways in which the different datasets can be used in conjunction with one another to improve inference.