Monday, August 22, 2011

Viz: Wealth and Health of Nations

The visualization I have chosen is from the website called gapminder. Gapminder is a project started by a passionate swedish doctor and statistician Hans Rosling. He has been trying to educate people and correct the popular perception about countries, public health and many other topics. He has developed a very intuitive form of visualization called the motion charts. They are very simple to understand yet very powerful in communicating time series related statistical data.

There are numerous motion charts on the gapminder website. I like the one on wealth and health of nations and it is in a way a good summary of how humanity has been doing since people started collecting data in large scale. The visualization extends the basic idea of scatter plot and packs a lot of information and perspectives in one place. The visualization has two axes. The X axis is the GDP per capita of a country. The Y axis is the life expectancy of an average person in a country. Each point in the graph which resembles a scatter plot to start with is a country. The size of the point represents the population of the country. There is also a time dimension in this visualization. The visualization is divided into fixed time slots. Each of these slots represents a year from 1880 to 2009. When you click on the play button in this visualization, It creates an animation of the points over the years. It is very easy to see that the world in general has gone to better health and more wealth over time.

The visualization has many features. We can interact with this visualization in different ways. if we hover over a particular point we can see its X and Y axis values. We can also see its population in the right bottom widget. You can pause the visualization anytime and start it again. You can zoom into parts of the chart even when it is animating and zoom out using the small arrow to the right corner of X axis. You can make the scatter plots leave a trace as they animate over time. There are some more features which appear on right side of the chart. There are features for more fine grained control. We can choose only a few countries and these points will be labeled and have brighter color. This is a good view to compare two countries or compare a country with the rest of the world. Similarly there is a widget to choose all countries from a continent on the right top. Each continent has a different color and this also acts as the legend for what the color of the bubbles represent.

There are many visualizations using the same motion chart paradigm on gapminder. It is a very popular website too. Hans Rosling is a regular visitor to the prestigious TED global conference. Every year he tries to bust a myth with a new motion chart. The visualizations have gone better and better every year. Here is a link to the TED video using a similar visualization.