The Diffusion of the Reaper: One More Time!

In the June 1977 issue of this Journal, Lewis R. Jones criticized my analysis of the diffusion of mechanical reaping and mowing machinery. Jones attempts to revive the threshold argument popularized by Paul David. In doing so Jones either confuses or ignores the main points I raised while concentrating on a peripheral issue of little significance.I raised three major issues. First, and of least importance, I revised the values of some of the parameters David used to estimate the threshold acreage. Jones correctly notes that I erred by reporting that the revised threshold was more than twice as large as that previously estimated; the correct calculation is about 93 percent, as Jones notes. If I were to write the paper again, I would correct this mistake. Nonetheless, my major conclusions on this issue are unaltered. Revising two of the parameters used to calculate the threshold acreage so that they better conform with the actual historical situation generates a threshold about twice as large as that previously estimated. I felt this discrepancy was sufficient to cast reasonable doubt on previous estimates, and I noted that similar revisions could be made of most of the parameters and variables used for such estimations (p. 333). Anyone who doubts this assertion should see Robert Ankli's excellent work on the subject.