Learning, Complementarities, and Asynchronous Use of Technology

This paper deals with processes that require several complementary inputs subject to improvements in quality. If after a quality upgrade one of these inputs requires a period of learning before it can be used effectively, then in general it will pay to purchase the inputs at different dates -- the purchases will be asynchronous. That is so because it is wasteful to tie up funds in the other inputs which will be underutilized until the date learning is over. We provide evidence that technology has been used asynchronously in the automobile industry, in the television broadcasting industry, in electricity supply, and in railways, and we argue that our model helps explain this evidence.