在Mankiw, Romer, Weil. A contribution to the empirics of economic growth, 1992一文411页中，

从Solow模型推出：ln(Y/L) = a + b1 ln(s) + b2 ln(n+g+delta) + e
作者假定s和n+g+delta 都与e不相关，给出的第一条理由是：


in any model in which saving and population growth are endogenous but preperences are isoelastic, saving rate (s) and population growth rate (n) are unaffected by error term (e). In other words, under isoelastic utility, permanent differences in the level of technology do not affect saving rates or population growth rates.


什么意思啊？


谢谢指点。