Binomial dispersion parameter.
phiWt.RdMME estimate of dispersion parameter phi.
Arguments
- fit
A glm object.
- subset.factor
Factor for estimating phi by subset. Will be converted to a factor if it is not a factor.
- fit.only
Return only the new fit? If FALSE, also returns the weights and phi estimates.
- show.warns
Show warnings
Value
A list with the following elements. fit: the new model fit,
updated by the estimated weights weights: vector of weights phi: vector
of phi estimates
Details
Estimates binomial dispersion parameter \(\phi\) by the method of
moments. Refits the model, weighting the observations by \(1/\phi\). Uses
quasibinomial family in glm().
References
Wedderburn RWM, 1974. Quasi-likelihood functions, generalized linear models, and the Gauss-Newton method. Biometrika 61:439-447.
Examples
birdm.fit <- glm(cbind(y, n - y) ~ tx-1, binomial, birdm)
RRor(phiWt(birdm.fit))
#>
#> 95% t intervals on 4 df
#>
#> PF
#> PF LL UL
#> 0.479 -0.537 0.823
#>
#> mu.hat LL UL
#> txcon 0.768 0.95 0.367
#> txvac 0.400 0.78 0.111
#
# 95% t intervals on 4 df
#
# PF
# PF LL UL
# 0.479 -0.537 0.823
#
# mu.hat LL UL
# txcon 0.768 0.95 0.367
# txvac 0.400 0.78 0.111
#