| arch {vars} | R Documentation |
Usagearch(x, lags.single = 16, lags.multi = 5, multivariate.only = TRUE)
Arguments
| x | Object of class ‘varest’; generated byVAR(), or an object of class ‘vec2var’; generated byvec2var(). |
| lags.single | An integer specifying the lags to be used for theunivariate ARCH statistics. |
| lags.multi | An integer specifying the lags to be used for themultivariate ARCH statistic. |
| multivariate.only | If TRUE (the default), onlythe multivariate test statistic is computed. |
vech(hat{u}_t hat{u}_t') = β_0 + B_1vech(hat{u}_{t-1} hat{u}_{t-1}') + ... + B_qvech(hat{u}_{t-q} hat{u}_{t-q}' + v_t)
whereby v_t assigns a spherical error process andvech is the column-stacking operator for symmetric matricesthat stacks the columns from the main diagonal on downwards. Thedimension of β_0 is frac{1}{2}K(K +1) and forthe coefficient matrices B_i with i=1, ..., q,frac{1}{2}K(K +1) times frac{1}{2}K(K +1). The nullhypothesis is: H_0 := B_1 = B_2 = ... = B_q = 0 and thealternative is: H_1: B_1 neq 0 or B_2 neq 0 or ... B_q neq0.The test statistic is:VARCH_{LM}(q) = frac{1}{2}T K (K + 1)R_m^2 quad ,
withR_m^2 = 1 - frac{2}{K(K+1)}tr(hat{Omega} hat{Omega}_0^{-1})quad ,
and hat{Omega} assigns the covariance matrix of the abovedefined regression model. This test statistic is distributed aschi^2(qK^2(K+1)^2/4).ValueA list with class attribute ‘varcheck’ holding thefollowing elements:
| resid | A matrix with the residuals of the VAR. |
| arch.uni | A list with objects of class ‘htest’containing the univariate ARCH-LM tests per equation. This elementis only returned if multivariate.only = FALSE is set. |
| arch.mul | An object with class attribute ‘htest’containing the multivariate ARCH-LM statistic. |
ReferencesDoornik, J. A. and D. F. Hendry (1997), Modelling DynamicSystems Using PcFiml 9.0 for Windows, International ThomsonBusiness Press, London.
Engle, R. F. (1982), Autoregressive conditional heteroscedasticitywith estimates of the variance of United Kingdom inflation,Econometrica, 50: 987-1007.
Hamilton, J. (1994), Time Series Analysis, PrincetonUniversity Press, Princeton.
L


雷达卡



京公网安备 11010802022788号







