But history tells us this was once the default in the time of Playfair. X was always time. You could use several Ys to show how wages were related to the price of wheat, annotations to show wars and monarchs…
Michael Friendly
Just how bad is a dual y-axis chart? I’m trying to explain that it’s one of the strongest rules in #dataviz but haven’t gotten further than the relative scaling is arbitrary & it implies correlation that may not be there.
