- When should I use a bubble chart vs a scatter plot?
- A scatter plot shows two variables (x, y). A bubble chart adds a third variable encoded as bubble size, and optionally a fourth as color. Use bubble charts when you have three or four dimensions to display and the extra complexity is worth the insight.
- How many data points work in a bubble chart?
- Bubble charts become hard to read beyond 30-50 points due to overlapping bubbles. For larger datasets, consider a scatter plot with color encoding, or interactive zoom/filter.
- Is area or radius mapped to the value?
- By default, area is proportional to the value — this is perceptually more accurate than radius mapping, where a 2x value would appear 2x wider but 4x larger in area. The tool maps area by default per visualization best practices.