Suppose a researcher was interested in learning more about parents' concerns when their children start elementary school. the researcher asks the parents of 800 randomly selected first graders in rural school district and the parents of 950 randomly selected first graders in an urban school district to rate their level of concern with the following statement: we are (a) not at all concerned (b) somewhat concerned or (c) very concerned about the nutrition level of school lunches. if we wanted to test whether there was an association between the response to the question and the type of school district that the first grader was attending, would this be a test of homogeneity or of independence?