FWIW Eviews used to not print p-values for the first lags I think, but maybe that has changed.
If I'm not mistaken these Portmanteau type of tests do not only require large T but also large m (max lag considered).
So the whole business becomes even murkier when m is so small that m-p-q becomes negative. Also using dof=m instead of m-p-q is not wrong asymptotically I believe, it's all "just" about small-sample corrections (which can be very important of course though).If your T is very very large you may calculate the Q stat for a very large m, and then given p and q not very large, a chi-square(m) and chi-square (m-p-q) may be similar. But usually we don't have so large T and we are interested in relatively low values of m. From m>p+q we have enough dof and the Q stat for a residuals series may have sense, and the asymptotic distribution is chi-square (m-p-q) different from the chi-square(m).
Ignacio Díaz-Emparanza Zuzendaria/Director ignacio.diaz-emparanza@ehu.eus 94 6013732 |
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