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