You can view the final interactive Flash version here:
Flowing Data recently did a tutorial “How to make Bubble Charts” using “R” which inspired me to add an additional bubble view to the interactive USA Unemployment map I previously produced. The bubbles represent the actual number of unemployed per the selected region depending on the other view modes selected i.e. State, County etc.
The really useful bit from the tutorial was the formula to calculate the radius of the bubble so that the Area of the circle represents the value and not the radius/diameter.
radius <- sqrt( unemployed/ pi )
I haven’t added a key yet but basically when the map is viewed at 100% a bubble with a 10 pixel diameter currently represents around 15,000 unemployed. As the user can zoom into the map and also the map re-sizes with the browser, than the key would need to scale proportionally with the map view to be relevant.
I have also fixed the bug on deep linking directly to US States. Check it out: