Measuringourignorance,onebookatatime: Newindicatorsoftechnologicalchange,1909–1949

New indicatorsoftechnologicalchangeintheUSbasedoninformationdrawnfromthe catalogueoftheLibraryofCongressfortheperiod1909–1949aredevelopedandusedto pinpointtherelationship,first,betweentechnicalchangeandeconomicactivity,and, second,betweenfluctuationsininnovativeactivityandtheGreatDepression.Although linksbetweentechnologicalchange,outputandproductivityarefound,resultssuggest thattheslowdownintechnologicalprogressintheearly1930sdidnotcontribute significantlytotheGreatDepression.Ontheotherhand,theremarkableaccelerationin innovationsafter1934didplayaroleintherecovery