Background:

I got a few values on the scale 0..1 and -1..1 that we have been asked to visualize as bubbles. The value 1.0 would be the largest sized bubble and 0.5 would half the size, and so on. Negativity would be represented by a color, say blue for positive, and red for negative.

Now, for "How to visualize a bubble with value 0?" we've been suggested "a small purple bubble". To me, it's counterintuitive -- if the value directly map to the area -- that a bubble of value 0 would be at all visible.

I know these values can also be visualized as bar charts on a y axis spanning both negative and positive. But who doesn't like bubbles, and I would like to explore any examples or standard ways of visualizing small values with area.

Questions:

To make this question less diffuse, here are my actual questions:

• Any way of showing 0 area?
• Would it be acceptable to show 0 area as small bubble, even though a small bubble actually has a non-zero area? Or would that metaphor impose problems somewhere?
• Are there any standard bubble features we could use to make small values more tangible?