特徵方程式大量估價法在台灣不動產市場之應用

An Application of Mass Appraisal and the Hedonic Equation in the Real Estate Market in Taiwan

如何精確估計不動產價格一直是房地產研究領域的一個熱門話題，而且不動產的放款更是銀行重要的業務範圍，精確估計不動產價值是維護授信品質的重要條件之一。同時，在巴賽爾協定的規範下，銀行業必須對擔保品定期檢視其市值以確保授信的品質，但由於一般銀行業者累積不動產擔保品的數量龐大，定期檢視與重估價值的變動，是一件非常花費人力與物力的工作。因此，大量估價法的需求就因應而生，因為一個良好的大量估價模型可以以低成本且有效率的方式來解決上述問題。在房地產實證研究的領域中，特徵方程式（hedonic equation）一直是受到研究者廣泛使用的估計工具，然大多針對某一現象或研究目的進行模型設計，較少在具有大量樣本下進行推估。本文將採用大量估價法（mass appraisal）與特徵方程式，針對估計建物價格的目的，說明如何建立變數的過程與限制，同時結合總體時間變化的影響，有效率且低成本的推估建物價格，並探討如何以不同指標檢驗預測能力的標準，提供進一步增加預測精準度的可行方案。

Estimating a housing price precisely is always an important issue both in real estate research and in practice by financial institutions. According to the Basel Accord, financial institutions have to review and to reassess their mortgage assets for a certain period of time to maintain asset quality and control risk. However, since it is costly to reassess a real estate property in the traditional way, it will be very troublesome and costly to reassess thousands of real estate mortgages for each institution from time to time. Therefore, constructing a mass appraisal model to reassess a large quantity of real estate mortgages has become a necessity for most financial institutions. In this paper we first build a mass appraisal model using the hedonic equation model, including housing characteristics, neighborhood attributes, and macroeconomic variables, and then apply a dataset with more than 50,000 real estate mortgages to construct a housing price equation. According to several statistics, including R-squared, the mean absolute percentage error (MAPE), and the hit rate, we find that the estimation results of our pricing model are quite satisfactory. This implies that mass appraisal could be a good model to apply in Taiwan.