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 --...

We analyze lifetime earnings histories of white males during 1960-2010 and categorize the labor force status of every worker as either working full-time, partially retired or fully retired. We find that the fraction of partially retired workers has risen dramatically (from virtually 0 to 15...

We construct key household and individual economic variables using a panel micro data set from the Russia Longitudinal Monitoring Survey (RLMS) for 1994-2005. We analyze cross-sectional income and consumption inequality and find that inequality decreased during the 2000-2005 economic recovery....

We introduce a tractable model of post-retirement saving behavior in which households have a precautionary motive arising from uninsured health status risks. The model distinguishes between annuitized and non-annuitized wealth, emphasizes the importance of asset composition in determining...

We analyze a long-term contracting problem involving common uncertainty about a parameter capturing the productivity of the relationship, and featuring a hidden action for the agent. We develop an approach that works for any utility function when the parameter and noise are normally distributed...

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...

Aside from the equilibrium that Hotelling (1931) displayed, his model of non-renewable resources also contains a continuum of bubble equilibria. In all the equilibria the price of the resource rises at the rate of interest. In a bubble equilibrium, however, the consumption of the resource peters...

Stock-market crashes tend to follow run-ups in prices. These episodes look like bubbles that gradually inflate and then suddenly burst. We show that such bubbles can form in a Zeira-Rob type of model in which demand size is uncertain. Two conditions are sufficient for this to happen: A declining...

The Q-theory of investment says that a firm's investment rate should rise with its Q. We argue here that this theory also explains why some firms buy other firms. We find that 1. A firm's merger and acquisition (Mamp;A) investment responds to its Q more -- by a factor of 2.6 -- than its direct...

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...