本研究利用Stock and Watson（2002）與Bai and Ng（2002）建立的擴散指數模型，從眾多總體變數中選取一些代表性的指標構成項目，並依據綜合指數法將各項構成項目合成一新基準循環以提升基準循環指標編製的精確性。實證結果發現，透過此模型選取而來的變數大多數屬實質變數，此結果與NBER編制景氣指標同時指數強調使用實質變數的概念是一致的。此外，利用上述指標構成項目所新編的數列，其所認定的峰谷時點更接近經建會公佈的峰谷時點。這結果顯示，本研究新編的指標數列確實可以幫助我們更加了解臺灣的景氣狀況。

The primary interest of this study is to evaluate the composite variables from the existing reference series and construct an alternative series which can better present the economic situation in Taiwan. Specifically, we applied the diffusion index model developed by Stock and Watson (2002) and Bai and Ng (2002) to select key variables among numerous macroeconomic variables for constructing the reference series. Our empirical evidence indicatets that some variables, including Real Gross Domestic Product, Industrial Production Index, Index of Producer's Shipment for Manufacturing, Sales Index of Wholesale, Retail and Food Services, Average Monthly Overtime in Industry and Services (Hours) and Real Customs-Cleared Exports, are good candidate variables for constructing the reference series. Also, compared with the peak and trough points in the business cycle suggested by the existing reference series, the peak and trough points in the business cycle identified from our alternative reference series are more consistent with those suggested by the Council for Economic Planning and Development in Taiwan. This implies that our alternative reference series is indeed a better business indicator of Taiwan economic situation.