VizTest is a package that identifies optimal confidence intervals for visual testing. This follows the suggestions in the following paper:

Armstrong II, David A. and William Poirier. (2025) “Decoupling Visualization and Testing when Presenting Confidence Intervals.” Political Analysis 33(3):252-257.

You can install the current stable version from CRAN and the development version of VizTest from GitHub with:

# install.packages("pak")
pak::pak("davidaarmstrong/VizTest")