In this survey, I discuss four sources of growth of knowledge: research, schooling, learning by doing, and training. In trying to disentangle what is important, I emphasize the following facts: (1) even the most advanced countries spend far more on adoption of existing technologies than on...

A satisfactory account of the postwar growth experience of the United States should be able to come to terms with the following three facts: -Since the early 1970's there has been a slump in the advance of productivity. -The price of new equipment has fallen steadily over the postwar period....

A new technology or product is often developed by the single entrepreneur. Whether he reaches the public offering stage or is acquired by a listed firm it takes time for the innovator to add value to the stock market. Indeed first, reduce the market's value because some firms -- usually large or...

We analyze mergers over the past century in a growth model that emphasizes technological change. We explain the positive relation between mergers and stock prices, the positive relation between internal growth of firms and their acquisitions, and the positive relation of mergers with other...

The term "new economy" has, more than anything, come to mean a technological transformation, and in particular its embodiment in the computer and the internet. These technologies are more human capital intensive than earlier ones and have probably hastened the pace of the shift in the U.S....

Firms that entered the stock market in the 1990s were younger than any earlier cohort since World War I. Surprisingly, however, firms that IPO'd at the close of the 19th century were just as young as the companies that are entering today. We argue here that the electrification-era and the IT-era...

Investment of U.S. firms responds asymmetrically to Tobin's Q: Investment of established firms -- `intensive' investment -- reacts negatively to Q whereas investment of new firms -- `extensive' investment -- responds positively and elastically to Q. This asymmetry, we argue, reflects a...

Electricity and Information Technology (IT) are perhaps the two most important general purpose technologies (GPTs) to date. We analyze how the U.S. economy reacted to them. The Electricity and IT eras are similar, but also differ in several important ways. Electrification was more broadly...

We model Moore's Law as efficiency of computer producers that rises as a by-product of their experience. We find that (a) because computer prices fall much faster than the prices of electricity-driven and diesel-driven capital ever did, growth in the coming decades should be very fast, and that...

We study 114 years of U.S. stock market data and find That there are large cohort effects in stock prices, effects that we label 'organization capital,' That cohort effects grew at a rate of 1.75% per year, That the debt-equity ratio of all vintages declined, That three big technological waves...