本研究主要係利用凱因斯理論及統計方法建立迴歸模型，試圖了解私人投資支出增加對台灣所得、利率、物價是否具顯著影響力。實主量分析上，以IS-LM、AD-AS理論為基礎，利用統計方法SPSS實證檢驗台灣近37年（1971年至2008年）之季資料，探討私人投資支出、市場利率、物價、所得之相互關聯性。實證結果顯示，若私人投資支出增加，所得GDP上升、利率會下跌、物價會上漲；反之可以發現，當私人投資支出下降時，所得也就會跟著減少。綜述得知私人投資支出與GDP、物價呈正向的變動關係，而私人投資支出與利率的影響呈反向的變動關係，且私人投資支出對GDP的解釋能力較高，在利率、物價的解釋能力較低。實證結果顯示與凱因斯IS-LM、AD-AS理論一致，私人投資支出增加，利率會下降，所得及物價會增加之結果一致。

This study applied Keynesian Theory and statistics methods to establish a regression model, in order understand whether an increase in private investment has any significant influence on GDP, interest rates and price in Taiwan. This empirical analysis was established on the basis of IS-LM and AD-AS theories. SPSS was utilized to perform tests on the quarterly data during the past 37 years (1971~2008) in Taiwan in order to explore relationships among private investment, interest rates, price and GDP. Findings, that an increase in Private investment would increase GDP, lower interest rates, and increase price. On the contrary, a drop in private investment and would reduce GDP. To sum up, there is a positive correlation between private investment and GDP, as well as between private investment and price. There is a negative correlation between private investment and interest rates. Meanwhile, private investment have high explanatory power over GDP and relatively low explanatory power over interest rates and price. The empirical results are consistent with Keynesian IS-LM and AD-AS Model. A rise in private investments and will reduce interest rates, and increase GDP and price.