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sstvars (version 1.1.0)

pick_regime: Pick regime parameters

Description

pick_regime picks the regime parameters \((\phi_{m,0},vec(A_{m,1}),...,vec(A_{m,p}),vech(\Omega_m))\)

Usage

pick_regime(
  p,
  M,
  d,
  params,
  m,
  cond_dist = c("Gaussian", "Student", "ind_Student", "ind_skewed_t"),
  identification = c("reduced_form", "recursive", "heteroskedasticity",
    "non-Gaussianity")
)

Value

Returns the vector...

If identification == "non-Gaussianity" or cond_dist %in% c("ind_Student", "ind_skewed_t"):

\((\phi_{m,0},vec(A_{m,1}),...,vec(A_{m,p}),vec(B_m))\).

If otherwise:

\((\phi_{m,0},vec(A_{m,1}),...,vec(A_{m,p}),vech(\Omega_m))\).

Note that neither weight parameters or distribution parameters are picked.

Arguments

p

the autoregressive order of the model

M

the number of regimes

d

the number of time series in the system, i.e., the dimension

params

a real valued vector specifying the parameter values. Should have the form \(\theta = (\phi_{1,0},...,\phi_{M,0},\varphi_1,...,\varphi_M,\sigma,\alpha,\nu)\), where (see exceptions below):

  • \(\phi_{m,0} = \) the \((d \times 1)\) intercept (or mean) vector of the \(m\)th regime.

  • \(\varphi_m = (vec(A_{m,1}),...,vec(A_{m,p}))\) \((pd^2 \times 1)\).

  • if cond_dist="Gaussian" or "Student":

    \(\sigma = (vech(\Omega_1),...,vech(\Omega_M))\) \((Md(d + 1)/2 \times 1)\).

    if cond_dist="ind_Student" or "ind_skewed_t":

    \(\sigma = (vec(B_1),...,vec(B_M)\) \((Md^2 \times 1)\).

  • \(\alpha = \) the \((a\times 1)\) vector containing the transition weight parameters (see below).

  • if cond_dist = "Gaussian"):

    Omit \(\nu\) from the parameter vector.

    if cond_dist="Student":

    \(\nu > 2\) is the single degrees of freedom parameter.

    if cond_dist="ind_Student":

    \(\nu = (\nu_1,...,\nu_d)\) \((d \times 1)\), \(\nu_i > 2\).

    if cond_dist="ind_skewed_t":

    \(\nu = (\nu_1,...,\nu_d,\lambda_1,...,\lambda_d)\) \((2d \times 1)\), \(\nu_i > 2\) and \(\lambda_i \in (0, 1)\).

For models with...

weight_function="relative_dens":

\(\alpha = (\alpha_1,...,\alpha_{M-1})\) \((M - 1 \times 1)\), where \(\alpha_m\) \((1\times 1), m=1,...,M-1\) are the transition weight parameters.

weight_function="logistic":

\(\alpha = (c,\gamma)\) \((2 \times 1)\), where \(c\in\mathbb{R}\) is the location parameter and \(\gamma >0\) is the scale parameter.

weight_function="mlogit":

\(\alpha = (\gamma_1,...,\gamma_M)\) \(((M-1)k\times 1)\), where \(\gamma_m\) \((k\times 1)\), \(m=1,...,M-1\) contains the multinomial logit-regression coefficients of the \(m\)th regime. Specifically, for switching variables with indices in \(I\subset\lbrace 1,...,d\rbrace\), and with \(\tilde{p}\in\lbrace 1,...,p\rbrace\) lags included, \(\gamma_m\) contains the coefficients for the vector \(z_{t-1} = (1,\tilde{z}_{\min\lbrace I\rbrace},...,\tilde{z}_{\max\lbrace I\rbrace})\), where \(\tilde{z}_{i} =(y_{it-1},...,y_{it-\tilde{p}})\), \(i\in I\). So \(k=1+|I|\tilde{p}\) where \(|I|\) denotes the number of elements in \(I\).

weight_function="exponential":

\(\alpha = (c,\gamma)\) \((2 \times 1)\), where \(c\in\mathbb{R}\) is the location parameter and \(\gamma >0\) is the scale parameter.

weight_function="threshold":

\(\alpha = (r_1,...,r_{M-1})\) \((M-1 \times 1)\), where \(r_1,...,r_{M-1}\) are the threshold values.

weight_function="exogenous":

Omit \(\alpha\) from the parameter vector.

identification="heteroskedasticity":

\(\sigma = (vec(W),\lambda_2,...,\lambda_M)\), where \(W\) \((d\times d)\) and \(\lambda_m\) \((d\times 1)\), \(m=2,...,M\), satisfy \(\Omega_1=WW'\) and \(\Omega_m=W\Lambda_mW'\), \(\Lambda_m=diag(\lambda_{m1},...,\lambda_{md})\), \(\lambda_{mi}>0\), \(m=2,...,M\), \(i=1,...,d\).

Above, \(\phi_{m,0}\) is the intercept parameter, \(A_{m,i}\) denotes the \(i\)th coefficient matrix of the \(m\)th regime, \(\Omega_{m}\) denotes the positive definite error term covariance matrix of the \(m\)th regime, and \(B_m\) is the invertible \((d\times d)\) impact matrix of the \(m\)th regime. \(\nu_m\) is the degrees of freedom parameter of the \(m\)th regime. If parametrization=="mean", just replace each \(\phi_{m,0}\) with regimewise mean \(\mu_{m}\).

m

which regime?

Details

Constrained models nor structural models are supported.