Recipe for Simulating Autoregressive Processes up

Recipe for Simulating Autoregressive Processes

Let

displaymath253

describe a stationary AR(p) process, where tex2html_wrap_inline257 is a white noise process with zero mean and variance tex2html_wrap_inline259 , and tex2html_wrap_inline261 is a sequence of AR coefficients. Given tex2html_wrap_inline263 , tex2html_wrap_inline265 , ..., tex2html_wrap_inline267 which are taken to be uncorrelated Gaussian deviates with zero mean and unit variance (obtained on a computer from a Gaussian random number generator), we desire to generate a realization of tex2html_wrap_inline209 , tex2html_wrap_inline211 , ..., tex2html_wrap_inline273 . To do so, we carry out the following steps.

  1. We first calculate the p-1 sequences tex2html_wrap_inline277 , tex2html_wrap_inline279 , ..., tex2html_wrap_inline281 and tex2html_wrap_inline283 by computing the following for k = p, p-1, ..., 2:

    displaymath289

  2. Second, we calculate

    displaymath291

  3. Third, we generate tex2html_wrap_inline209 , tex2html_wrap_inline211 , ..., tex2html_wrap_inline297 via

    eqnarray57

  4. Finally, the remaining N-p values are generated using

    displaymath301

Let us consider two concrete examples, namely, the AR(2) and AR(4) processes given by Equations (45) and (46a). The AR(2) process has coefficients tex2html_wrap_inline303 and tex2html_wrap_inline305 and has tex2html_wrap_inline307 . Application of step 1 yields

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while step 2 yields

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We thus would generate the AR(2) process using

eqnarray104

For the AR(4) process, we have tex2html_wrap_inline313 , tex2html_wrap_inline315 , tex2html_wrap_inline317 and tex2html_wrap_inline319 , with tex2html_wrap_inline321 . Application of step 1 yields

eqnarray119

while step 2 yields

eqnarray151



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Feathers McGraw
Mon Jan 25 14:14:14 PST 1999