Infrastructure is a result of both public and private investment, with private investment ranging betw een 25 per cent to 70 per cent of total infrastructure investment in different countries. But since data on infrastructure are scant and typically do not provide a comprehensive total of private and public investments, public infrastructure is used as a proxy in a large number of studies, thereby potentially leading to undercounting of total infrastructure stocks of countries in existing empirical analyses. This problem is exacerbated by the fact that many countries have not maintained reliable public infrastructure investment figures until recently, which creates issues around comparability. Hence, existing estimates do not capture the efficiency of infrastructure and service quality, which is a very important determinant of growth.