Q. How do I know if a chart or graph representing data that I don’t hold the sole copyright would be considered a fair use to include in my dissertation?

Data and data representations aren’t protected, so neither are charts/tables/graphs/figures that do nothing more than express underlying facts.

However, figures may be protected as original works of authorship where there are creative choices made that do more than represent the underlying data (choices dictated by more than functional considerations). For more information, refer to this copyrightability of tables and charts document.