Higher math skills are robustly correlated with higher profits among Kenyan shop owners

Earlier work finds very high rates of return to inventories in the context of the small retail sector in Kenya. Inventories are positively associated with math skills. Since inventories and profits are positively correlated, math skills predict profits as well. In this paper, using sophisticated survey data on small-scale Kenyan retailers, Kremer et al. (2013) find that math skills are also robustly correlated with profits conditional on inventories. 

By Michael Kremer, Jonathan Robinson and Olga Rostapshova (2013)