Dual axis graphs are often used to handle two data sets with different sizes. For example, the following dual axis graph shows the trends in world GDP (left y-axis) and Germany's GDP (right y-axis).

Here’s a lovely chart with dual y-axes to provide a quick visual check. Note that I’m plotting murder vs. mis trust in government, since that’s supposed to be the actual driving factor: ...

Moneybox Economic Policy Institute Produces Dual Axis Chart That Proves Nothing Affects Economic Growth By Matthew Yglesias June 04, 20132:41 PM ...