不動產估價人員系統行為偏誤檢驗－－以市場比較法為例

An Empirical Study of Appraiser’s Behavior Systematic Bias on the Sales Comparison Approach

市場比較法是估價人員最常使用的方法，但在估價過程中主觀判斷部分相對較多也最易引起爭議。過去市場比較法研究著重在估價理論與技術改進，以減少主觀判斷造成的隨機偏誤，然而，研究指出行為偏誤造成的系統偏誤，其持續性的偏誤對於估價偏誤有重要影響。過去探討估價行為的研究，受限於資料樣本取得，幾乎都是以問卷或實驗得到結果，而非實證結果。本文建立二個系統行為偏誤之假說，研究樣本為實際估價報告書，以鄒檢定（Chow Test）及似無相關檢定（Seemingly Unrelated Regression）檢驗，發現勘估標的估值與比較標的市場成交值兩模型係數有顯著差異，支持估價人員有系統行為偏誤。此外，本文也發現評估不同市場時，系統行為偏誤程度亦不同，估價人員於評估拍賣價格時，因估價經驗與比較案例較少，較傾向參考比較案例，系統行為偏誤亦較小，僅面積係數有差異；反之，評估正常市場價格時，因估價經驗與比較案例較多，估價系統行為偏誤較大，區位、使用類型及面積係數皆有差異。 This paper reviews the behavior literature regarding real estate appraisers andsummarizes the two systematic bias hypotheses for departure from normativemodels. The study is based on appraisers’ reports analyzes for the appraisalvaluation and the market transaction by hedonic price models. Among the 112appraisal reports of the transaction data of 230 comparables and the valuations of224 subjects, the results reveal the effect of the variables on the appraisal valuationare not consistent with those of the market transaction. In addition, comparing theappraisers’ behavior on the general market with the auction market, the result foundthe differences between the valuation models and the transaction models that areless than the models on the auction market. The empirical evidences support thetwo systematic bias hypotheses and can be explained plausibly by the appraisers’behavioral contention.

This paper reviews the behavior literature regarding real estate appraisers andsummarizes the two systematic bias hypotheses for departure from normativemodels. The study is based on appraisers’ reports analyzes for the appraisalvaluation and the market transaction by hedonic price models. Among the 112appraisal reports of the transaction data of 230 comparables and the valuations of224 subjects, the results reveal the effect of the variables on the appraisal valuationare not consistent with those of the market transaction. In addition, comparing theappraisers’ behavior on the general market with the auction market, the result foundthe differences between the valuation models and the transaction models that areless than the models on the auction market. The empirical evidences support thetwo systematic bias hypotheses and can be explained plausibly by the appraisers’behavioral contention.