I support the basic idea of Mr Rajendra Rampersaud’s letter on total factor productivity (SN June 15). I cannot argue against Mr Rampersaud’s letter, except to note that I have some technical differences with respect to what can determine per capita income growth in the early stages of a country’s development. Indeed, growth can result from natural resource extraction in the short-term without any significant technological and managerial progress, which TFP growth implies. However, in the long-term, as my friend Rajendra argued,