Stage one fits a long AR(m) by OLS and keeps its residuals as innovation proxies; stage two regresses w_t on p own lags and q lagged proxies. Two OLS solves, no iteration.
References
Hannan and Rissanen (1982), Biometrika 69(1), 81-94; the ARIMA model is Box, Jenkins and Reinsel (1994), Chapter 4. Standard published form; neither source is in the local corpus and neither was read.
Examples
V <- c(1, 2, 3, 4, 5, 6, 7, 8)
Arimahr(V)
#> $phi
#> [1] 1
#>
#> $theta
#> [1] -8.478067e-16
#>
#> $intercept
#> [1] 1
#>
#> $sigma2
#> [1] 4.733165e-30
#>
#> $resid
#> [1] 8.881784e-16 8.881784e-16 0.000000e+00 -1.776357e-15
#>
#> $m
#> [1] 3
#>
#> $p
#> [1] 1
#>
#> $q
#> [1] 1
#>
#> $d
#> [1] 0
#>
#> $nobs
#> [1] 4
#>
#> $method
#> [1] "Hannan-Rissanen ARMA estimation (Hannan-Rissanen 1982)"
#>
#> attr(,"class")
#> [1] "morie_rich_result" "list"
