Since a high correlation coefficient does not necessarily guarantee the efficiency of a model, Table 8 presents statistical indexes of the estimated coastal current velocities by the ANFIS and ANN models (the bias and RMSE criteria). As seen from the table, the ANFIS estimations were slightly biased. From the RMSE calculated by the models it can be concluded that ANN models are more accurate than the ANFIS models. In other words, the ANN models estimate both longshore and cross-shore current velocities with an acceptable accuracy. The error of the ANN models as well as the ANFIS models at the windy condition was higher than that at the stormy condition.

Table 8

Error of the ANFIS and ANN models in approximating coastal current velocities at all three conditions

.	ANN .		ANFIS .
	RMSE(m/s) .	bias(m/s) .	RMSE(m/s) .	bias(m/s) .
General condition
	0.451	−0.0137	0.242	−0.0124
	0.0743	−0.0123	0.0604	−0.0162
Stormy condition
	0.568	−0.0192	0.434	−0.0188
	0.1196	−0.0168	0.1232	−0.0212
Windy condition
	0.9508	−0.0193	0.353	−0.0137
	0.1278	0.0026	0.145	0.0043

.	ANN .		ANFIS .
	RMSE(m/s) .	bias(m/s) .	RMSE(m/s) .	bias(m/s) .
General condition
	0.451	−0.0137	0.242	−0.0124
	0.0743	−0.0123	0.0604	−0.0162
Stormy condition
	0.568	−0.0192	0.434	−0.0188
	0.1196	−0.0168	0.1232	−0.0212
Windy condition
	0.9508	−0.0193	0.353	−0.0137
	0.1278	0.0026	0.145	0.0043

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