[gerdesj]

"dual axis charts can often be a great choice."

I generally find that a second Y axis creeping in is perhaps an indicator to stop and have a really deep think about what you are trying to achieve. You might try doing a 3D graph for example where x, y1, y2 becomes x, y, z then spin and explore. However you have to remember that y1 and y2 are both dependent on x (by definition) so when you put y2 to a separate dimension, it is not independent from y1 (or is it?)

There are no hard and fast rules when it comes to spin doctoring via graphs, and as the old adage doesn't go: There are liars, damned liars and politicians.