What role as the U.S. government had in the determination of races? Why can this be important in scientific research?

What will be an ideal response?

The U.S. government creates categories for races in its everyday functioning. People are expected to select their race from a limited set of categories and not every governmental agency identifies the same categories as races. Thus there is inconsistency in government categories.
In addition, people currently self-select their racial category. Depending on the purpose of their choice of races, the same person might select different categories. Further, across the decades, the government has used different criteria for assigning race to an individual and has even used categories that have dropped out of use (e.g., quadroon, octoroon, mulatto).
This is a problem in research because scientists often base the racial categories in their research on governmental guidelines. As such, they use categories that are not necessarily reliable. If their categories aren't reliable, then can't be valid.