新興凱因斯學派總合供需模型下最適物價目標區之研究──以商品市場需求面干擾為例

本文利用Frenkel and Rodriguez（1982）、Sutherland（1995）與Lai and Chang（2001）的理論架構為藍本，同時考量工資完全指數化特質的新興凱因斯學派開放經濟體系Lucas總供函數，使用Lai and Chang（2001）、Lai et al.（2008, 2011）等的目標區理論「蜜月效果幾何圖解法」與陳秀華（2004）、廖培賢（2018）等的「最適目標區幾何圖解法」，據以進行在一個資本呈現不完全移動的浮動匯率小型開放經濟體系裡，一旦商品市場需求面遭逢隨機性衛擊時，貨幣當局採行物價目標區體制對相關的總體經濟變數是否具有穩定效果功效之實是面議題與貨幣當局一旦企圖追求社會福利損失極小化的前提下，又該如何挑選最適物價目標區間寬窄之規範面議題的討論。本文的主要結論為當經濟體裡遭逢商品市場需求面隨機性衛擊時，貨幣當局物價目標區體制的實施對本國物價及本國名目利率都具有穩定效果，對匯率水準是否具有穩定效果端視資本移動程度相對大小而定，另對本國產出則視定義的不同，可有也可無穩定效果。再者，不管貨幣當局相對關心本國物價抑或本國產出水準的波動，一旦貨幣當局企圖追求整體社會福利損失的極小化時，則必須選擇最適物價目標區間為零的本國物價固定體制。

This paper presents an open economy macroeconomic model based generally on those developed by Frenkel and Rodriguez (1982), Sutherland (1995) and Lai and Chang (2001). Specifically, this paper uses the geometric approaches developed by Lai and Chang (2001), Chen (2004), Lai et al. (2008, 2011) and Liaw (2018) to determine the optimal price band when the monetary authority minimizes social welfare loss. Under this approach, if the economy faces demand shocks in the commodity and foreign exchange (foreign interests rate) markets, this paper concludes that the monetary authority must adopt a fixed domestic price level strategy (the optimal price band is zero). This is independent of whether the monetary authority cares about fluctuations in the domestic price and output levels.