open cps91.gdt
mlinear <- ols lwage 0 hours educ black age
genr age2 = age^2
mquad <- ols lwage 0 hours educ black age age2
genr b1 = $coeff(age)
genr b2 = $coeff(age2)
genr aeffect = b1*age + b2*age2
genr deriv = b1 + 2*b2*age
genr awmax = -b1/(2*b2)