Testing Keynes’ aggregate investment function in Germany, Japan, the UK, and the US

Despite the central importance of investment spending to Post Keynesian macroeconomics, only a few scholars have attempted empirical studies of Keynes' approach. This surely arises from the difficulty that emerges when trying to model agents' expectations. Graziani claims to have developed a viable method, which has been further tested by Harvey and Pham. However, they focus exclusively on the US. This paper extends their approach to other nations, adding Germany, Japan, and the UK to the mix (and--with a slightly different specification—France and Italy in an appendix) for. In addition, an adjustment is made to the earlier articles' measures of agents' forecasts, making them even more consistent with Keynes' arguments. This new approach proved superior in every case and the overall results were excellent with the exception of a few issues with the UK.