Model identification I. Stationarit I. Theoretical autocorrelation function (TAC II. Theoretical Partial autocorrelation Function(TPAc IV. Sample partial Autocorrelation Function (SPAC V. Sample autocorrelation Function (SAC4 Model Identification I. Stationarity II. Theoretical Autocorrelation Function (TAC) III. Theoretical Partial Autocorrelation Function (TPAC) IV. Sample Partial Autocorrelation Function (SPAC) V. Sample Autocorrelation Function (SAC)