[Retracted] Prediction of Concrete Compressive Strength Based on the BP Neural Network Optimized by Random Forest and ISSA

Table 6

Predicted results of 6 models.

Index	Model
	RF-BPNN	RF-PSO-BPNN	RF-SSA-BPNN	RF-CSSA-BPNN	RF-ISSA-BPNN	ISSA-BPNN
MAE	5.6620	4.9291	5.4083	5.1226	4.3798	4.9887
RMSE	7.5048	6.7247	6.8324	6.4402	5.6687	6.5417