預售屋與成屋爲台灣住宅市場之二大次市場，由於預售屋兼具期貨特質，預售屋與成屋市場間的價格關係一直爲房地市場參與者所關切。觀察基差及其變化有助於了解二者之替代性，並可發掘不同次市場的特質。過去雖有針對基差進行的研究，但並未將具不同供需環境的地區視爲異質，對深入觀察地區性次市場在基差的差異及其市場意義仍有不足。本研究針對台北市及台北縣民國85年至87年間，自國泰建設取得預售屋之開價資料，以及台灣不動產成交行情公報中之成屋成交價格資料，建立特徵價格模型並分別對台北市及台北縣估計其基差。實證結果顯示，影響台北市縣房價之顯著因素均爲面積、區位、樓高和屋齡；而觀察台北市縣三年之基差，台北市分別爲10.57萬／坪、11.82/坪萬、11.84萬／坪；台北縣基差各爲2.72萬／坪、1.42萬／坪、2.1萬／坪。且在價差比方面，以台北市來看，從民國85至87年分別爲71%、68%、68%；而台北縣則爲84%、92%、87%。由此可知，台北市在預售屋與成屋之價差關係大於台北縣，突顯基差議題在地區次市場分析的重要性。

Pre-sale and existing house are major submarket in Taiwan housing market. Because the pre-sale house is possessed the attribute of futures, the relationship of price difference in pre-sale and existing house is concerned with real estate participators. It is helpful to understand the substitute of pre-sale and existing house that observe the basis and its change, and we also discovery the attributes within submarket. For the past study of basis, they didn’t think heterogeneous between local submarket so that there is little knowledge about basis and its market meanings in local submarket. This study build Hedonic price model to estimate basis of Taipei city and Taipei county from 1996 to 1998 using the list prices of pre-sale house from Cathy co. and transaction prices of existing house from Gigahouse co.. The result is showed that the price factors of building area, location, total floor, building age are significantly in Taipei city and Taipei county. The basis are 105.7K/pin, 118.2K/pin and 118.4K/pin from 1996 to 1998 in Taipei city. And we also get 27.2K/pin, 14.2K/pin and 21K/pin from the same period in Taipei county. For the ratio of price difference, we get 71%, 68% and 68% in Taipei city, and 84%, 92% and 87% in Taipei county. We think that the relationship of Taipei city is large than Taipei county, and this issue is very important in local submarket.