Historical GDP of world economies back to 1945: What are the most complete and reliable data sets? I need the historical GDP of all modern countries (or at least the vast majority) from 1945 to now. It seems the world bank data only starts in 1960 or later. I found Angus Maddison's data, but I don't know how reliable it is. Can anyone tell me if it is reliable? Are there other good data sets for my needs?
As far as I know Angus Madison's GDP figures are one of the most reliable sources of historical data, even if data construction is as always diputable. The Review of Income and Wealth published a rigorous debate between Angus Maddisson and Carsten A. Holz regarding Maddison's estimates on China's growth. 

You may also find useful the  Historical Bilateral Trade and Gravity Data set (TRADHIST) provided by the CEPII, which partly uses Maddison's data. TRADHIST gathers more than 1.9 million bilateral trade observations for the 188 years from 1827 to 2014. TRADHIST also provides about 42,000 observations on aggregate trade, and about 14,000 observations on GDPs and exchange rates respectively. This data set is publicly available.