I wanted to show the large forces that drive global inequality and poverty, those changes that affect, in one fell swoop, the quality of life for many of the 6.3 billion people on earth.
I have two candidates for massive worldwide change: First, economic growth; second, China. The graphic illustrates both.
(a larger dynamic animation can be invoked if the inline version above isn't clear enough in your browser; or just click anywhere in the figure).
The vertical axis measures millions of people living on less than 1 US dollar a day (actually, the threshold is 1 International Dollar a day, but close enough). The horizontal axis is per capita income in the country or bloc of countries: Economic growth means movement rightwards horizontally. The size of a bubble measures the total population. EAP indicates East Asia and the Pacific Region; LAC, Latin America and the Caribbean; MENA, Middle East and North Africa; SAS, South Asia; and SSA, Sub-Saharan Africa. Additionally, China and India are given separately in the graphic.
The animation follows these continental groupings over time, from 1990 through 2004, and shows how as growth occurs, poverty falls.
In principle, if inequality within a continent or within China or India increased sufficiently with economic growth, then the corresponding bubble in the picture might well rise vertically. All that means then is that, in that case, even though average income increases with growth, inequality increases so overwhelmingly that the joint growth-inequality process grinds ever more people into ever greater bone-crunching poverty.
(To be clear, inequality does not have to increase with economic growth. But many people and quite a few economists think it might---hence the so-called tradeoff between equality and efficiency. The data do not speak very strongly on this, in either direction. But I think such a putative regularity is of little consequence for the point here.)
Almost uniformly, the graphic shows inequality is unable to rise enough to overcome the benefits of economic growth. As a matter of logic alone, of course, it might: an actual, large instance in the animation is China between 1996 and 1999: In that 3-year period the China bubble moved rightwards and upwards. So there's nothing in the arithmetic that rules out the possibility. But it is unusual. As time proceeds, almost uniformly, the bubbles move southeasterly, shifting rightwards and dropping towards the floor. This is a very good thing. Economic growth reduces poverty.
In the animation, right at the start of the sample Eastern Europe and Central Asia (ECA) implodes leftwards, just as post-Communist transition began. But then after that pretty much only the rightwards movement is visible. Compared to China, that other 1-billion people economy India, up through 2004, still hadn't done very much. Sub-Saharan Africa (SSA) all this time basically did nothing but percolate upwards: It didn't grow and it saw vast numbers of its people fall ever further into grinding poverty.
In 1981 1.47 billion people on earth lived on less than 1 dollar a day. By 2004 that number had fallen to 0.97 billion, a reduction of half a billion. (If you don't like these numbers, you come up with better ones. In economic research it takes a model to beat a model, so simply complaining that a model isn't a good model or is unrealistic doesn't get you very far. So too whining that an estimate isn't a good estimate.) The animation shows that pretty much all of that worldwide poverty reduction is due to just ... China.
Since this animation, like all digital goods, is infinitely expansible, I also presented it at a British-Malaysia Chamber of Commerce lunch and as part of a lecture at the British Council in Malaysia, both also in August, as part of Malaysia's 50th anniversary celebration of its independence from Britain. (The animation is also on youtube and you can put a version on your cellphone if you like.)
The underlying data are from Chen and Ravallion (2007) "Absolute Poverty Measures for the Developing World" and from World Development Indicators (2006) online. Further analysis is in Quah (2007) "Life in Unequal Growing Economies". Related discussion appears in Quah (2003) "One Third of the World's Growth and Inequality".
I generated the animation by
dvips -pp 5-10 -o - 2007.08-SERC-lug-dq.dvi | ps2pdf - - | convert -delay 80 - 1-2007.08-SERC-lug-dq.gif
i.e., using standard tools