Self-Tuning Inference Model for Settlement in Shield Tunneling: A Case Study of the Taipei Mass Rapid Transit System’s Songshan Line

Table 6

Error indices.

Performance measure	Formula
Mean absolute percentage error (MAPE)
Coefficient of correlation (R)
Mean absolute error (MAE)
Root mean squared error (RMSE)
Reference index (RI)

y is the actual value. y′ is the predicted value. n is the number of data samples.