There are a lot of empirical studies on the reaction of taxpayers to taxes.
In my own study on this, I collected 11 or 12 serious empirical studies that used two best practices methods in particular. The economic profession agrees with the fact that these are good methods and that the data used are excellent. So they are good studies.
The reaction of taxpayers was clearly observed. We know what it is. The results of the study can be used to make fairly accurate estimates.