生產性政府支出與總體經濟動態均衡

Abstract

本文採用離散時間的兩部門模型，模型中包含消費與投資兩個生產部門，且投資部門具有外部性。我們將政府支出分別引入這兩部門之中，使得投資、消費部門生產皆具有正外部性。接著我們藉由解出的模型動態體系以及形成各均衡狀態的條件，探討政府如何透過調整消費與投資支出比例來影響模型動態體系的安定性。將校準數值代入模型後，我們發現若要使經濟體呈現馬鞍點均衡，則政府的消費或投資支出比例分別需要大於一定的數值，且為避免經濟體呈現多重均衡路徑所需的最小政府消費與投資支出之間具有抵換關係。在敏感度分析中，我們發現政府在消費部門的支出比例不會影響模型動態均衡狀態，也就是政府無法透過調整消費支出來改變模型動態體系的安定性。接著我們發現當投資部門外部性大於零時，為避免經濟體呈現不穩定均衡所需的最小政府投資支出比例會隨著投資部門外部性的增加而遞增。

We adopted a two sectors model in this article , and the production sectors in the model including consume and investment sectors with positive productive externalities . We induce government spending to the production sectors , that is , the government spending is productive . The government expenditures of investment and consumption are set as constant fractions of the total output . This article examines the quantitative interrelations between sector composition of productive public spending and equilibrium determinacy , we found that a sufficiently high public consume or invest spending can stabilize the economy against endogenous fluctuation driven by agents’ animal spirit . Furthermore , when each type of government spending is set as constant ratio , we found that there is a trade off between public consumption versus public invest spending to yield saddle path stability and equilibrium uniqueness .