## Graphical Gotchas

Scatterplots and overplotting

• When many points are plotted and "overplot", e.g. cover one another, it is common to set an alpha < 1. However, alpha has a minimum, so this is not always a fix. KDEs are better.

Log scales

Data that varies over orders of magnitude should most likely be on a log-scale.

• Zeros make log-scales hard though. The wrong solution is to exclude zero points. The better solution is to add an offset to each value, which is a tradeoff in that it adds some bias. People often add 1, but it's problem-specific. Often adding the observed non-zero minimum is best.