Proportion and percentage data are tricky to analyze.
Much like count data, they look like they should work in a linear model.
They’re numerical. They’re often continuous.
And sometimes they do work. Some proportion data do look normally distributed so estimates and p-values are reasonable.
But more often they don’t. So estimates and p-values are a mess. Luckily, there are other options. [Read more…] about Zero One Inflated Beta Models for Proportion Data