Answer:
The element that I would call statistical data that an author uses in an argumentative essay to support the author's position is:
Textual evidence
Step-by-step explanation:
Statistical data is information objectivaly translated into numbers. Therefore it can't be considered a claim. Because claims are ideas, and in our case data is not an idea is a representation of reality. Also, thesis statement would be a theory that we believe can explain reality about a certain problem or phenomenom. While statistical data is the gathered information that explains that topic. So it is not only a belief it is reality.