In SimplexNumerica, a bubble chart is just a scatter chart with variable size symbols.
In this chart, two scatter layers with variable size glass sphere symbols are shown.
This chart is the same as the previous chart, except semi-transparent colors are used, so you can see through the bubbles. This is useful if the bubbles can overlap extensively.
This chart uses solid spheres as bubbles.
A bubble chart using semi-transparent circular symbols.
In SimplexNumerica, bubbles are not limited to spheres or circles. Other shapes can also be used.
Furthermore, the horizontal and vertical dimensions can be scaled independently.
SimplexNumerica even supports using custom images as bubbles.