Third, in the medium term, sources of output growth are different. In the industrialized economies, output growth is driven by productivity increase which, in turn, is a function of the level of investment and the pace of technical progress. In developing economies output growth is, or at least should be, driven by labour absorption through employment creation in the non-agricultural sector and, in some part, through a shifting of labour from low productivity employment to higher productivity employment in the manufacturing sector or the services sector. In this process, investment plays a critical role. Of course, in most successful developing countries, which eliminate disguised unemployment in the agricultural sector, approximate to full employment in the industrial sector, or close the technological gap between themselves and industrialized countries, productivity increase becomes the primary source of output growth. And, in the long run, growth in output per capita requires productivity gains regardless of labour market conditions. This is borne out by the experience of massive productivity growth in Japan, Korea and, now, China.