open ects_nls.gdt
ols y 0 x1 x2 -o
genr alpha = coeff(0)
genr beta = coeff(x1)
genr a0 = alpha
genr b0 = beta
nls y = alpha + beta*x1 + (1/beta)*x2
 deriv alpha = 1
 deriv beta = x1 - x2/(beta*beta)
end nls --vcv
genr alpha = a0
genr beta = b0
nls y = alpha + beta*x1 + (1/beta)*x2
end nls --vcv

