Some economists criticise the theory, stating that endogenous factors, such as government policy, are much more influential in economic growth than exogenous factors. For example, Alexander Gerschenkron states that governments can substitute for missing prerequisites to trigger catch-up growth. A hypothesis by economic historians Kenneth Sokoloff and Stanley Engerman suggested that factor endowments are a central determinant of structural inequality that impedes institutional development in some countries. Sokoloff and Engerman proposed that in the 19th century, countries such as Brazil and Cuba with rich factor endowments such as soil and climate are predisposed to a guarded franchise with limited institutional growth. Land that is suitable for sugar and coffee such as Cuba experienced economies of scale from the establishment of plantation that in turn created the small elite families with vested interest in guarded franchise. The exogenous suitability of land for wheat versus sugar determines the growth rate for many countries. Therefore, countries with land that is suitable for sugar converge with other countries that also have land that is suitable for growing sugar.