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I need to estimate parameters of an AR model which is in the form of AR(1,11) it means that coefficients of AR orders from order 2 until order 10 are zero. How can I estimate these two parameters in R since arima function only accepts p as the order of the AR component. Note that this model has a different structure than Seasonal AR.

Thanks

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Wouldn't this be possible by using the FIXED option in the ARIMA syntax? In this case,

output <- arima(x, order=c(11,0,0), fixed = c(NA,0,0,0,0,0,0,0,0,0,NA))

The order statement supplies the number of lags for the AR process, and the fixed vector is "NA" for any lags you want to estimate and zero otherwise.

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  • $\begingroup$ thank you, I didn't know that we can assign "NA" for parameters that we need. I will try this. $\endgroup$ – Fred Apr 24 '13 at 21:15
  • $\begingroup$ Sure thing, let me know if that resolves your problem. $\endgroup$ – Corcovado Apr 24 '13 at 21:21
  • $\begingroup$ Yes it did but we should add another NA for q order like this output <- arima(x, order=c(11,0,0), fixed = c(NA,0,0,0,0,0,0,0,0,0,NA, NA)) $\endgroup$ – Fred Apr 24 '13 at 21:30

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