In any contentious debate, getting two sides to agree to the same set of facts can be an elusive, frustrating endeavor.
And sometimes, the more you push on facts, the more squishy they become.
Take, for instance, a report out this week on chronic teacher absenteeism by the Thomas B. Fordham Institute.
It used federal data from the Department of Education's Office for Civil Rights and found these indisputable facts: Nationally, 28.3 percent of teachers in traditional public schools are chronically absent, compared with 10.3 percent in the charter sector.
A similar rate difference holds in Pennsylvania, where 32.1 percent of traditional public school teachers are considered chronically absent vs. 8.2 percent in charters.
According to the Office for Civil Rights, a teacher who is out for more than 10 days in a school year is considered chronically absent.
The data for both sectors is based on federal OCR data from 2013-14 that was released in 2016. Absences are counted as instructional days missed for sick leave and personal time.