Productive physical investment and growth: testing the validity of the AK model from a panel perspective

In this article, we analyse the relationship between productive physical investment and economic growth from a panel perspective for a sample of 61 countries spanning the period 1950 to 1992. The analysis can be thought of as two-fold. First, we test the empirical validity of AK models following the logic by Jones (1995 Jones, CI. 1995. Time series properties of endogenous growth models. Quarterly Journal of Economics, 110: 495–525. [Crossref], [Web of Science ®] , [Google Scholar]). For that purpose, we determine the degree of persistence of physical investment rates and growth by employing recently developed panel unit-root tests that enable us to make more reliable inferences about the existence of stochastic trends in the series. Second, we estimate the long-run effect of physical investment on growth by using panel data techniques rather than cross-section regressions. Overall, our findings cast doubts on the rejection of the empirical validity of the AK model, as suggested by Jones’ analysis.