The Comparative Performance of Q-type and Dynamic Models of Firm Investment: Empirical Evidence from the UK

In this paper two models of investment stemming from the neoclassical theory are derived in a unifying framework. The Q type models view the stock market valuation of a firm as an all-encompassing variable determining its investment decisions, while the Euler equation for investment highlights the dynamic nature of firms’ decisionmaking. A sample of 779 UK manufacturing companies listed in the London Stock Exchange in the period 1971-1990 is used to compare the empirical fit of the two different models of investment. Despite a number of difficulties, the Q model appears to be empirically superior delivering the desirable consistency between theory and data.