供求

從勞動力需求和供給中得出總產出

  • March 7, 2021

我正在閱讀以下論文:

http://eml.berkeley.edu//~moretti/growth.pdf

我陷入了等式(7)

企業的生產函式為 $ Y_{i}=A_{i}L_{i}^{\alpha}K_{i}^{\eta}T_{i}^{1-\alpha-\eta} $

勞動力供給是 $ W_{i}=V\frac{P_{i}^{\beta}}{Z_{i}}=V\frac{\bar{P_{i}}^{\beta}L_{i}^{\beta \gamma_{i}}}{Z_{i}} $

勞動力需求是 $ L_{i}=(\frac{\alpha^{1-\eta}\eta^{\eta}}{R^{\eta}}\frac{A_{i}}{W_{i}^{1-\eta}})^{\frac{1}{1-\alpha-\eta}}T_{i} $

論文說,如果我們強加總勞動力需求等於總勞動力供給(正規化為一),那麼總產出 $ Y=\sum_{i}Y_{i} $ 是

$ Y=(\frac{\eta}{R})^{\frac{\eta}{1-\eta}}[\sum_{i}(A_{i}[\frac{\bar{Q}}{Q_{i}}]^{1-\eta})^{\frac{1}{1-\alpha-\eta}}T_{i}]^{\frac{1-\alpha-\eta}{1-\eta}} $

這一步對我來說看起來很激烈。如何從上述條件推導出總產出?

採用 $ W_{i}=V \cdot \frac{P_{i}^{\beta}}{Z_{i}}=VQ_i $ , 然後$$ L_{i}=\left(\frac{\alpha^{1-\eta} \eta^{\eta}}{R^{\eta}} \cdot \frac{A_{i}}{(V_{i} Q_{i})^{1-\eta}}\right)^{\frac{1}{1-\alpha-\eta}} \cdot T_{i} $$和$$ \sum L_i = {\left({\frac{\alpha}{V}}\right)}^{\frac{1-\eta}{1-\alpha-\eta}} {\left({\frac{\eta}{R}}\right)}^{\frac{\eta}{1-\alpha-\eta}} \sum\left(\frac{A_i}{Q_i^{1-\eta}}\right)^{\frac{1}{1-\alpha-\eta}}T_i = 1 $$ $$ \frac{V}{\alpha} = {\left({\frac{\eta}{R}}\right)}^{\frac{\eta}{1-\eta}} \left(\sum\left(\frac{A_i}{Q_i^{1-\eta}}\right)^{\frac{1}{1-\alpha-\eta}}T_i\right)^{\frac{1-\alpha-\eta}{1-\eta}} $$.

將 FOC 用於勞動, $ W_i=\alpha \frac{Y_i}{L_i} $ , 然後$$ \sum Y_i = \frac{V}{\alpha}\sum L_iQ_i = \frac{V}{\alpha} \bar{Q} $$, 並替換 $ \frac{V}{\alpha} $ 用上面的方程,你得到方程(7)。

引用自:https://economics.stackexchange.com/questions/42939