theta.md {MASS}R Documentation

Estimate theta of the Negative Binomial by Deviance

Description

Given the estimated mean vector, estimate theta of the Negative Binomial Distribution by equating the deviance to the residual degrees of freedom. Analogue of a moment estimator.

Usage

theta.md(y, u, dfr, limit = 20, eps = .Machine$double.eps^0.25)

Arguments

y Vector of observed values from the Negative Binomial.
u Estimated mean vector.
dfr Residual degrees of freedom (assuming theta known).
limit Limit on the number of iterations.
eps Tolerance to determine convergence.

Value

The required estimate of theta, as a scalar.

See Also

glm.nb, theta.ml, theta.mm

Examples

## Not run: theta <- theta.md(y, fitted(fm), dfr = 123)

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