MVAR estimates parameters of the Multi-Variate AutoRegressive model Y(t) = Y(t-1) * A1 + ... + Y(t-p) * Ap + X(t); whereas Y(t) is a row vecter with M elements Y(t) = y(t,1:M) Several estimation algorithms are implemented, all estimators can handle data with missing values encoded as NaNs. [AR,RC,PE] = mvar(Y, p); [AR,RC,PE] = mvar(Y, p, Mode); with AR = [A1, ..., Ap]; INPUT: Y Multivariate data series p Model order Mode determines estimation algorithm OUTPUT: AR multivariate autoregressive model parameter RC reflection coefficients (= -PARCOR coefficients) PE remaining error variances for increasing model order PE(:,p*M+[1:M]) is the residual variance for model order p All input and output parameters are organized in columns, one column corresponds to the parameters of one channel. Mode determines estimation algorithm. 1: Correlation Function Estimation method using biased correlation function estimation method also called the 'multichannel Yule-Walker' [1,2] 6: Correlation Function Estimation method using unbiased correlation function estimation method 2: Partial Correlation Estimation: Vieira-Morf [2] using unbiased covariance estimates. In [1] this mode was used and (incorrectly) denominated as Nutall-Strand. Its the DEFAULT mode; according to [1] it provides the most accurate estimates. 5: Partial Correlation Estimation: Vieira-Morf [2] using biased covariance estimates. Yields similar results than Mode=2; 3: buggy: Partial Correlation Estimation: Nutall-Strand [2] (biased correlation function) 9: Partial Correlation Estimation: Nutall-Strand [2] (biased correlation function) 7: Partial Correlation Estimation: Nutall-Strand [2] (unbiased correlation function) 8: Least Squares w/o nans in Y(t):Y(t-p) 10: ARFIT [3] 11: BURGV [4] 13: modified BURGV - 14: modified BURGV [4] 15: Least Squares based on correlation matrix 22: Modified Partial Correlation Estimation: Vieira-Morf [2,5] using unbiased covariance estimates. 25: Modified Partial Correlation Estimation: Vieira-Morf [2,5] using biased covariance estimates. 90,91,96: Experimental versions Imputation methods: 100+Mode: 200+Mode: forward, past missing values are assumed zero 300+Mode: backward, past missing values are assumed zero 400+Mode: forward+backward, past missing values are assumed zero 1200+Mode: forward, past missing values are replaced with predicted value 1300+Mode: backward, 'past' missing values are replaced with predicted value 1400+Mode: forward+backward, 'past' missing values are replaced with predicted value 2200+Mode: forward, past missing values are replaced with predicted value + noise to prevent decaying 2300+Mode: backward, past missing values are replaced with predicted value + noise to prevent decaying 2400+Mode: forward+backward, past missing values are replaced with predicted value + noise to prevent decaying
Package: tsa