The study of the incidence of disease in a population that cannot be directly manipulated is called:

When congress limited the size of washington, dc to 10 square miles, they could not have predicted the growth of the federal bureaucracy. which of the following conditions, do you suppose, is directly related to the inability of the federal city to expand? (select all that apply.)

Greg goes to a high school and observes the way students talk to each other. he makes notes on the words used, the atmosphere of the school and the way the students present themselves to each other. this is an example of a( research method.

Why was frederick douglass encouraged by the dred scott decision?