Thanks for everyone's contribution . West, I think you make a very good point that philosophy, culture, legal system and even the style of governmental governance may be significant repressors for GDP growth rate. Solow model ignores those factors may be the fact that Solow planned to set up a basic and simple modeling framework at the very beginning. He first assumed that population growth rate; investment rate (both human and physical investment), depreciation rate, and more importantly technology growth rate are main explanatory variables for economic growth. It's a good exercise to run a simple OLS regression by econometrics software like Gauss and Eviews5.0 to see which factors are more significant. However, if we found that all variables are I(1) and indeed co- integrated we may like to use an VAR Error Correction Model to look deeply on its short run dynamics.
