10.115 Obesity and earnings An AP story (April 9, 2005) with headline Study: Attractive People Make More stated that “A study concerning weight showed that women who were obese earned 17 percent lower wages than women of average weight.”

a. Identify the two variables stated to have an association.

b. Identify a control variable that might explain part or all of this association. If you had the original data including data on that control variable, how could you check whether the control variable does explain the association?