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Module arma

Module arma 

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Hannan–Rissanen (1982) recursive ARMA order selection and initial coefficient estimation (their stages 1–2; the efficient third stage is left to the bindings/estimation layer).

Stage 1 fits a long Yule–Walker autoregression (order chosen by AIC, their practical recommendation) and extracts innovation estimates ε̂. Stage 2 regresses x_t on p lags of x and q lags of ε̂ for every candidate (p, q) on a common sample and minimises log σ̃²_{p,q} + (p + q) log T / T (their BIC choice, eq. 1.11).

Their 1983 Biometrika correction (70, p. 303) reports that Theorem 3’s proof is in error and the stage-2 selection as published can converge to values larger than (p₀, q₀), typically when the MA polynomial has zeros near the unit circle; the fix they give — repeating stage 2 with the residuals ε̃(t) of eq. (1.12) in place of ε̂ — restores convergence and is applied here by default (erratum_pass). The common-factor degeneracy makes the stage-2 design matrix singular exactly when p > p₀ and q > q₀ — such candidates are skipped when the Cholesky fails, which is itself the paper’s monitoring advice.

Structs§

HrConfig
Configuration of hannan_rissanen.
HrResult
Output of hannan_rissanen.

Functions§

hannan_rissanen
Hannan–Rissanen stages 1–2: select (p, q) and return the (consistent, not efficient) stage-2 coefficient estimates.