TECHNOLOGICAL PROGRESS UNDER LEARNING BY IMITATION*
分析知识中隐性成分很大时，技术知识通过直接人际模仿传播，技术进步率取决于同一知识网络中的创新者数量。假设知识扩散反映贸易地理模式，贸易逐步扩张会导致技术进步率突然上升。
I analyze technological progress when knowledge has a large tacit component so that transmission of knowledge takes place through direct personal imitation. It is shown that the rate of technological progress depends on the number of innovators in the same knowledge network. Assuming the diffusion of knowledge to mirror the geographical pattern of trade—the greater the trade between two sites, the greater the probability that technical knowledge flows between them—I show that a gradual expansion of trade causes a sudden rise in the rate of technological progress.