1. You have data from an extensive medical survey on health and economic status. A cross section of 500 men provides information on wages in f per week, age in years a and an index of fitness f. You run the following regression of In wages on the fitness index: Inw = 6.1-0.31fts (1) (i) Interpret the coefficient of fitness. Why Economists usually use In wage instead of wage as dependent variable. Explain your answer. You then add age to the regression with the following results: Inw =5.3+0.07a+0.12f+ & (2) (ii) Explain carefully why and how adding age to the regression can change the size of the estimated fitness effect. Do the results indicate that age must be negatively or positively correlated with fitness in this sample