摘要
本文使用 CIA 模型，引進短期和長期公債，分析扭轉操作政策 (operation twist) 對總體經濟的效果。所謂扭轉操作，即中央銀行在不改變貨幣供給量下，同時買進長債並賣出短債的政策作為，此一政策試圖透過改變資產組合來影響實質經濟活動。 當只有消費為現金財時，扭轉操作會使市場上短債增加，流動性變多，短期內帶動價格上升。因流動性增加，導致實質消費上升，但資本累積減少，對經濟體有刺激效果。若消費和投資同為現金財，會促使投資增加，資本累積上升，刺激經濟活動效果更顯著。此外，若短債可作為交易媒介，則經濟體會出現短債利率低於長債利率的正斜率殖利率曲線，凸顯短債在流動性上優於長債而出現的利率差異。
並列摘要
This paper employs a standard CIA (cash-in-advance) model to analyze the dynamic effects of the operation twist (henceforth, OT) policy, that is, the central bank swaps short-term securities for long-term securities, while holding money growth unaltered. In a setting where short-term assets are considered as a means of payment or liquidity, the policy of OT can generate various real effects on the economy. First, if consumption is the only cash goods in the economy, then OT will lead to an increase in prices shortly and enhance liquidity, increasing consumption, while investment deteriorates. The stimulating effects of the policy will show up. In the second case where both consumption and investment are subject to CIA constraint, the OT policy will increase both, especially investment, and generate greater stimulating effects consequently. Finally, if short-term securities are treated as a form of liquidity, then short-term interest rates can be lower than the long-term rates, leading to a positively-sloped yield curve.