Comment on "The Adversity/Hysteresis Effect: Depression-Era Productivity Growth in the U.S. Railroad Sector"

William Kerr, The Rate and Direction of Inventive Activity Revisited (University of Chicago Press, 2011), https://www.nber.org/books-and-chapters/rate-and-direction-inventive-activity-revisited/comment-adversityhysteresis-effect-depression-era-productivity-growth-us-railroad-sector-kerr.