We estimate the correlation between a person$$s level of earnings and his$/$her level of education.$$We include age, and wealth status $($rich and poor$)$ as controls. The equation is represented as $-$Earnings $=\backslash$alpha $+\backslash$beta $1$Education $+\backslash$beta $2$Age $+\backslash$beta $3$Rich $+\backslash$beta $4$P oor $+$This estimation equation essentially suffers from the problem of