Identify all variables in these research situations and classify them by their level of measurement. Which variables are independent and which are dependent?

a. A researcher is wondering about racial preferences in dating among college students and asks a large sample of undergraduates about their own racial self-identification, gender, and age, and to rank some racial-ethnic categories (stated as: white, black, Latino, Asian) in terms of desirability as potential dates.

b. For adolescents, is one's level of sexual activity related to academic success in high school? A sample of teenagers was interviewed about the number of different romantic relationships they have had, the number of times they have had sexual intercourse, and their high school GPA.

c. Several hundred voting precincts across the nation have been classified in terms of the percentage of minority voters and voting turnout as well as percentage of local elected officials who are members of minority groups. Do precincts with higher percentages of minority voters have lower turnout? Do precincts with higher percentages of minority representation among local elected officials have higher turnout?

d. As nations become more affluent (as measured by per capita income), does the percentage of children enrolled in school increase? Is this relationship different for boys and girls?

e. Does the level of support for gun control vary by level of education? Does this relationship vary by gender, region of the country, or political party preference? Support for gun control was measured by a five-point scale that ranged from "strongly in favor" to "strongly opposed."