Replacing crosses with circles

Further information can be displayed in a scatterplot by replacing the crosses (or other symbols) with circles whose diameter varies according to another measurement. This kind of diagram is most effective if the third measurement is some description of the size of the 'individuals'.

The areas of the circles should be proportional to their size measurement, not their diameters.

In Official Statistics publications, the 'individuals' are usually countries or other geographical regions. The size of the circles often reflects the population of the places, but it could depend on their area, Gross Domestic Product (GDP), number of AIDS cases or many other 'size' measurements.

Birth rate and life expectancy in Africa

The scatterplot below shows the birth rates and life expectancies of all countries in Africa in 2005.

Select Circles from the pop-up menu at the bottom. The circle size is initially determined by the land areas of the countries.

Select Population and GDP from the pop-up menu to place greater emphasis on the countries with high population or GDP.

Since the countries vary so much in size, the circles give a fairer representation of the relationship between birth rate and life expectancy in Africa.