Hi, there. In the last video, you saw why the state was so central to the analysis that we're doing in this course. We also saw why we needed to collect the basic set of data. Well, in this video, we're going to configure the world in terms of population. We're going to examine its growth and its distribution over the 20th century. And we're also going to assess the accuracy in measuring it. Now on the 11th of October 2011, the world's seven billionth citizen, Danica May Camacho was born in the Philippines. By the end of the day though, she'd been joined by at least four other claimants, one in India, one in Canada, and two in Russia but at opposite ends of the country. Later the UN Secretary General Ban Ki-moon conceded that the choice had been symbolic, that the day chosen had been arbitrary. And that he didn't know who the seven billionth citizen was or where and when he or she had been born. And as if to prove the capricious nature of demographic forecasting, Danica May had been in such a hurry to be the 7 billionth citizen that she was actually born at two minutes before midnight on October the 10th. Seven billion inhabitants. Back in 1900, it was estimated that the world's population had stood at 1.6 billion. In 1960, it was still only 3 billion. But not only had the world's population exploded over the 20th century, it had been accompanied by marked shift in its distribution. The largest relative gains were in Africa and Asia, and the greatest relative decline was in Europe. The causes of that growth in Africa and Asia had been a large fall in the death rates, and this was because of the impact of modern medicine, and the control of killer epidemics. And the major beneficiary had been the young, who then survived and had children of their own. Now these same factors also impacted on Europe, but here they were accompanied by a fall in the birth rate, as women delayed the start of childbearing and reduced family size. The effect in many European countries and in Japan as well, was to reduce the birth rates below replacement levels. Now all of this presents two kinds of challenges. For countries with a high birth rate, they have to find productive employment for new entrants to the labor markets. While countries with a lower birth rate will have to cope with an aging population and the increased costs of health expenditure that this entails. And they have to do both of these with a much smaller potential productive base. Population is seen as one of the simplest numbers. People are people and they can be counted. And for this reason, they're supposed to be more accurate than the other data that we have. But this second assumption depends largely on the efficiency of the statistical agencies responsible for assembling the data. In the poorer countries, especially, they have fewer resources that they can divert to these kind of activities. And generally, the less trustworthy the results. Often births and deaths remain unrecorded, especially in remoter rural areas. And a census is costly, and is often politically fraught as an undertaking. It's not just a question then of the funds devoted to counting population that matters, the political context can also play a role. For example, when politics is tribal, there may be incentives to inflate the census returns, if the country's demographics determine the distribution of parliamentary seats, or form the basis for government expenditure. For example, in Kenya there had been in 2009 that led to 1,000 deaths and more than a half a million people displaced. The count in the northeast was nullified because it was felt the figures had been inflated. In Nigeria, the UN has completely ignored the census data altogether and produces regularly its own estimates on the base of extrapolation. For almost all countries, the most recent data everywhere is probably pretty close to reality. But this isn't necessarily true at a local level. And this is important, I always tell my students be very careful when the disaggregated data does not add up to the aggregated data. For example, in Shanghai, only one year before the official census in 2010, the authorities estimated the city's population to be 19.2 million. It turned out to be 23 million. Many more migrants from the countryside had stayed on than had been estimated. But the effect of this error was that the authorities had somehow misplaced the equivalent of the entire workforce of Bulgaria. You probably haven't heard of Newham in London but it's in the shadow of the Olympic stadium. In 2009, the authorities had estimated the population to be 246,000. The census results 2012 revealed a population of 308,000. An error of 25% which had a direct impact on levels of funding. And the reason was that migrants into the area was staying longer than they had a decade earlier. The police, by the way, estimated if you added the illegal migrants, you'd have a figure closer to 320,000. Illegal or irregular migration is another source of demographic uncertainty, also on a national scale. Since these people have evaded being identified, there's no real way to count them. Most estimates of illegal migration derive from the numbers caught. But that might actually reveal the success or failure enforcement, rather than the numbers actually successfully entering the country. After all, they're not caught. The estimates for illegal migration in the European Union range from 1.9 to 3.8 million, and for the United States the estimate is 11 and a half million. So let's pull all of these ideas together. We've seen that the world's population has more than quadrupled since 1900. We've seen that this was accompanied by a shift in its distribution towards Africa and Asia. We've also looked at why this growth occurred and pointed to the problems that that has entailed. And we've described some of the factors, institutional and political, that have influenced the accuracy of the statistics. In the next video, we'll start to examine the world's output as measured by its GDP, its gross domestic product. Now, in order to help you configure the world population, we've prepared a visualization, a map of the world's demographics. We invite you to have a look at it now.