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Table 4

Values of performance indices for the existing equations

Investigator	R	RMSE	MAPE	BIAS	SI
Dey & Sarkar (2006)	0.425	0.102	0.332	−0.003	0.268
Sarkar & Dey (2005)	0.080	0.280	0.489	−0.007	0.736
Lim & Yu (2002)	0.282	0.388	0.828	0.027	0.903
Aderibigbe & Rajaratnam (1998)	0.197	1.313	2.986	−0.035	3.119
Chatterjee et al. (1994)	0.144	0.496	0.427	−1.012	6.740
Altinbilek & Basmaci (1973)	0.045	13.292	58.017	−0.107	2.480
Valentin (1967)	0.442	1.617	0.770	−0.020	0.618

Investigator	R	RMSE	MAPE	BIAS	SI
Dey & Sarkar (2006)	0.425	0.102	0.332	−0.003	0.268
Sarkar & Dey (2005)	0.080	0.280	0.489	−0.007	0.736
Lim & Yu (2002)	0.282	0.388	0.828	0.027	0.903
Aderibigbe & Rajaratnam (1998)	0.197	1.313	2.986	−0.035	3.119
Chatterjee et al. (1994)	0.144	0.496	0.427	−1.012	6.740
Altinbilek & Basmaci (1973)	0.045	13.292	58.017	−0.107	2.480
Valentin (1967)	0.442	1.617	0.770	−0.020	0.618