| Abstract: | Sahal tested two hypothesis in his initial investigation of long-term technological development. These two hypothesis are learning by doing and scale of utilization. Sahal framed both hypothesis in a derived Gompertz form. He subsequently suggested the use of the Koyck form for the learning hypothesis, as well. He did not use it, however, because of relatively untractable correction difficulties that arise when estimating with it. This study refines Sahal's methodology and investigative procedure. It significantly fails to empirically disconfirm either long-term hypothesis in both the Gompertz and Koyck form. This is a result that, generally speaking, Sahal's work did not achieve. The artifacts the long-term technological development of which this study investigates are the commercial aircraft of what basically constitutes the old domestic trunk organization and the diesel-electric rail locomotives of the Class I roads. Upon establishing the explanatory significance of Sahal's hypothesis, this study generates acceptable forecasts of further technological development. Finally, this study compares learning's impact on the pace of technological change of both aircraft and diesel-electric locomotive technology. The methodology and procedure employed in this study, although possibly limited in application, substantially refine and improve Sahal's previous effort. |
