dot-_get_phi_start: Internal Helper to Calculate Initial Phi

In betaARMA: Beta Autoregressive Moving Average Models

Internal Helper to Calculate Initial Phi

Description

Calculates the initial value for the precision parameter phi based on the residuals of an initial 'lm.fit' object, following Ferrari & Cribari-Neto (2004).

This helper uses the *exact* mathematical logic from the original 'start_values.R' file to ensure identical numerical output.

Usage

._get_phi_start(fit, n_eff, linkinv, mu.eta)

Arguments

fit	An 'lm.fit' object.
n_eff	The effective number of observations used in the fit.
linkinv	The inverse link function.
mu.eta	The derivative of the mean w.r.t. eta (d(mu)/d(eta)).

Value

A single numeric value for phi_start.

betaARMA documentation built on March 29, 2026, 5:08 p.m.