A taller bar chart exalts its height, while a wider one diminishes the perception of the variations in height.
I have a bar chart where I try to demonstrate this idea -> http://ltw1556.web.cs.unibo.it/bias_barChartRatio.html
but I also want to display a "Golden Ratio", a wise proportion of width/height to show to some users.
How do I find this ratio?
1) Assuming the data is correct as you said, I want to extinguish the extreme effects of both the flatter plot and the lofty one. Your answer sounds great (therefore I'm not going to make a flat chart), but how do I know if I'm going too far in lengthening the height of the chart?
For example, is
Width: 800px, Height: 400px tall enough or should I go further in height in order to make dips more observable? Isn't there a surefire way of choosing the height, depending on the width?
2) The purpose of this chart was to clearly represent the growing trend of Oil Consumption. To be honest, I've randomly chosen some data from the BP report in order to prove a point: how the Width/Height ratio can change the perception of the data and how this can be used for lying with charts (the flatter plot could be used for corroborating lies).
Having said that, do you think I should change type of chart or simply change data?