pi_AR_perc              Prediction intervals based on AR-perc algorithm
pi_AR_proot             Prediction intervals based on AR-proot
                        algorithm
pi_BJ                   Prediction intervals based on the Box-Jenkins
                        method
pi_CB                   Prediction intervals based on the CB algorithm
pi_PP                   Prediction intervals based on PP algorithm
pi_PRR                  Prediction intervals based on the PRR algorithm
pi_QAR_perc             Prediction intervals based on QAR-perc
                        algorithm
pi_QAR_proot            Prediction intervals based on QAR-proot
                        algorithm
pi_TS                   Prediction intervals based on the TS algorithm
pi_X                    Prediction intervals based on X algorithm
