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bigtime (version 0.1.0)

sparseVARMA: Sparse Estimation of the Vector AutoRegressive Moving Average (VARMA) Model

Description

Sparse Estimation of the Vector AutoRegressive Moving Average (VARMA) Model

Usage

sparseVARMA(Y, U = NULL, VARp = NULL, VARpen = "HLag", VARlseq = NULL,
  VARgran = NULL, VARalpha = 0, VARMAp = NULL, VARMAq = NULL,
  VARMApen = "HLag", VARMAlPhiseq = NULL, VARMAPhigran = NULL,
  VARMAlThetaseq = NULL, VARMAThetagran = NULL, VARMAalpha = 0, h = 1,
  cvcut = 0.9, eps = 10^-3)

Arguments

Y

A \(T\) by \(k\) matrix of time series. If k=1, a univariate autoregressive moving average model is estimated.

U

A \(T\) by \(k\) matrix of (approximated) error terms. Typical usage is to have the program estimate a high-order VAR model (Phase I) to get approximated error terms U.

VARp

User-specified maximum autoregressive lag order of the PhaseI VAR. Typical usage is to have the program compute its own maximum lag order based on the time series length.

VARpen

"HLag" (hierarchical sparse penalty) or "L1" (standard lasso penalty) penalization in PhaseI VAR.

VARlseq

User-specified grid of values for regularization parameter in the PhaseI VAR. Typical usage is to have the program compute its own grid. Supplying a grid of values overrides this. WARNING: use with care.

VARgran

User-specified vector of granularity specifications for the penalty parameter grid of the PhaseI VAR: First element specifies how deep the grid should be constructed. Second element specifies how many values the grid should contain.

VARalpha

a small positive regularization parameter value corresponding to squared Frobenius penalty in PhaseI VAR. The default is zero.

VARMAp

User-specified maximum autoregressive lag order of the VARMA. Typical usage is to have the program compute its own maximum lag order based on the time series length.

VARMAq

User-specified maximum moving average lag order of the VARMA. Typical usage is to have the program compute its own maximum lag order based on the time series length.

VARMApen

"HLag" (hierarchical sparse penalty) or "L1" (standard lasso penalty) penalization in the VARMA.

VARMAlPhiseq

User-specified grid of values for regularization parameter corresponding to the autoregressive coefficients in the VARMA. Typical usage is to have the program compute its own grid. Supplying a grid of values overrides this. WARNING: use with care.

VARMAPhigran

User-specified vector of granularity specifications for the penalty parameter grid corresponding to the autoregressive coefficients in the VARMA: First element specifies how deep the grid should be constructed. Second element specifies how many values the grid should contain.

VARMAlThetaseq

User-specified grid of values for regularization parameter corresponding to the moving average coefficients in the VARMA. Typical usage is to have the program compute its own grid. Supplying a grid of values overrides this. WARNING: use with care.

VARMAThetagran

User-specified vector of granularity specifications for the penalty parameter grid corresponding to the moving average coefficients in the VARMA: First element specifies how deep the grid should be constructed. Second element specifies how many values the grid should contain.

VARMAalpha

a small positive regularization parameter value corresponding to squared Frobenius penalty in VARMA. The default is zero.

h

Desired forecast horizon in time-series cross-validation procedure.

cvcut

Proportion of observations used for model estimation in the time series cross-validation procedure. The remainder is used for forecast evaluation.

eps

a small positive numeric value giving the tolerance for convergence in the proximal gradient algorithms.

Value

A list with the following components

Y

\(T\) by \(k\) matrix of time series.

U

Matrix of (approximated) error terms.

k

Number of time series.

VARp

Maximum autoregressive lag order of the PhaseI VAR.

VARPhihat

Matrix of estimated autoregressive coefficients of the Phase I VAR.

VARphi0hat

Vector of Phase I VAR intercepts.

VARMAp

Maximum autoregressive lag order of the VARMA.

VARMAq

Maximum moving average lag order of the VARMA.

Phihat

Matrix of estimated autoregressive coefficients of the VARMA.

Thetahat

Matrix of estimated moving average coefficients of the VARMA.

phi0hat

Vector of VARMA intercepts.

References

Wilms Ines, Sumanta Basu, Bien Jacob and Matteson David S. (2017), "Sparse Identification and Estimation of High-Dimensional Vector AutoRegressive Moving Averages" arXiv preprint <arXiv:1707.09208>.

See Also

lagmatrix and directforecast

Examples

Run this code
# NOT RUN {
data(Y)
VARMAfit <- sparseVARMA(Y) # sparse VARMA
y <- matrix(Y[,1], ncol=1)
ARMAfit <- sparseVARMA(y) # sparse ARMA
# }

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