I've just come across a new OECD economic working paper on growth theory: Solow or Lucas? Testing growth models using panel data from OECD countries. Authors Jens Arnold, Andrea Bassanini and Stefano Scarpetta test whether the growth experience of a sample of OECD countries over the past three decades is more consistent with the human-capital augmented Solow model of exogenous growth, or with an endogenous growth model à la Uzawa-Lucas with constant returns to scale to “broad” (human and physical) capital. Here's their methodology:
We exploit the different non-linear restrictions implied by these two models to discriminate between them. Using pooled cross-country time-series data, we specify our growth regression by imposing cross-country homogeneity restrictions only on long-run coefficients, while letting the speed of convergence and short term dynamics to vary across countries.
The results suggest a strong effect of human capital accumulation: the estimated long-run effect on output of one additional year of education (about 6-9%) is also within the range of the estimates obtained in microeconomic analyses of the private returns to schooling. Our estimated speed of convergence is too fast to be compatible with the augmented Solow model, while is consistent with the Uzawa-Lucas model with constant returns to scale. This main finding is robust to several robustness tests.