Hartmann, D., Zagato, L., Gala, P., & Pinheiro, F. L. (2021). Why did some countries catch-up, while others got stuck in the middle? Stages of productive sophistication and smart industrial policies. Structural Change and Economic Dynamics, 58, 1-13. https://doi.org/10.1016/j.strueco.2021.04.007Development studies on the middle-income trap have highlighted the challenges for developing economies to transform their productive systems from simple towards high value-added activities. Here, we use trade data of 116 countries to quantify the stages of productive sophistication and reveal the critical phase that countries encounter at intermediate levels of economic sophistication. Our results reveal that only five countries (i.e. Ireland, Israel...