For which of these research situations would you most likely calculate a correlation coefficient?

A) independent variable = blood alcohol level; dependent variable = reaction time
B) independent variable = type of car owned; dependent variable = annual income
C) independent variable = gender; dependent variable = favorite type of music
D) independent variable = city of residence; dependent variable = political affiliation

Calculating a correlation coefficient measures the strength and direction of the relationship between two continuous variables. In option A, the independent variable (blood alcohol level) and dependent variable (reaction time) are both continuous, making it appropriate to calculate a correlation coefficient. The other options involve at least one categorical variable, making a correlation coefficient not the most appropriate statistical measure.