We take the standard machine replacement model and introduce uncertainty about the productivity differential of new vintages made available as time passes. In particular, agents are uncertain about the quality of their match with a new vintage until they adopt it. Uncertainty allows us to...

Evidence of the statistical significance of profits in Q regressions remains one of the principal findings in the empirical investment literature. This result is taken to support the view that capital market imperfections are an important element for understanding investment. This paper...