Introduction to Modern Economic Growth general patterns they show are typically consistent with evidence from a variety of different sources Nevertheless, there are points of contention For example, as Figure 1.12 shows, Maddison’s estimates show a slow but relatively steady growth of income per capita in Western Europe starting in 1000 This is disputed by many historians and economic historians A relatively readable account, which strongly disagrees with this conclusion, is provided in Pomeranz (2001), who argues that income per capita in Western Europe and China were broadly comparable as late as 1800 This view also receives support from recent research by Allen (2004), which documents that the levels of agricultural productivity in 1800 were comparable in Western Europe and China Acemoglu, Johnson and Robinson (2002 and 2005) use urbanization rates as a proxy for income per capita and obtain results that are intermediate between those of Maddison and Pomeranz The data in Acemoglu, Johnson and Robinson (2002) also confirms the fact that there were very limited income differences across countries as late as the 1500s, and that the process of rapid economic growth started sometime in the 19th century (or perhaps in the late 18th century) There is a large literature on the “correlates of economic growth,” starting with Barro (1991), which is surveyed in Barro and Sala-i-Martin (2004) and Barro (1999) Much of this literature, however, interprets these correlations as causal effects, even when this is not warranted (see the further discussion in Chapters and 4) Note that while Figure 1.16 looks at the relationship between the average growth of investment to GDP ratio and economic growth, Figure 1.17 shows the relationship between average schooling (not its growth) and economic growth There is a much weaker relationship between growth of schooling and economic growth, which may be because of a number of reasons; first, there is considerable measurement error in schooling estimates (see Krueger and Lindahl, 2000); second, as shown in in some of the models that will be discussed later, the main role of human capital may be to facilitate technology adoption, thus we may expect a stronger relationship between the level of schooling and economic growth than the change in schooling and economic growth (see Chapter 10); finally, the relationship between the level of schooling and economic growth may be partly spurious, in the sense that it may be capturing the influence of some other omitted factors also correlated with the level of 34