The article explores how public investments affect productivity in OECD countries from 1975 to 2002. By analyzing data from 21 countries, the researchers found that public capital has a positive impact on GDP, with an elasticity between 0.05 and 0.15. They also discovered common factors driving the relationship among variables, indicating a strong connection between public capital and productivity. The results remained consistent even when considering spillovers from other countries and controlling for factors like human capital, patents, and R&D capital.