Abstract:An unbiased estimation method based on original series and accumulated series for extended grey model (EGM) is developed, and the formula is proposed for calculating maximum predictable time scale of grey model. Unbiased extended GM (UEGM) has the characteristics of numerical stability, modeling objectivity and unbiased property. The steep slope engineering of Xiaowan Hydropower Station is studied as a case. The results show that the UEGM (1, M) model is better than the UGM (1, 1) and the EGM (1, M) models in precision and reliability.\
Liu Zhiping,and He Xiufeng. UNBIASED ESTIMATION OF EXTENDED GREY MODEL AND ITS APPLICATION TO FORECAST OF DEFORMATION OF STEEP SLOPES[J]. jgg, 2008, 28(1): 41-44.