glmmTMB (version 0.2.3)

nbinom2: Family functions for glmmTMB

Description

Family functions for glmmTMB

Usage

nbinom2(link = "log")

nbinom1(link = "log")

compois(link = "log")

truncated_compois(link = "log")

genpois(link = "log")

truncated_genpois(link = "log")

truncated_poisson(link = "log")

truncated_nbinom2(link = "log")

truncated_nbinom1(link = "log")

beta_family(link = "logit")

betabinomial(link = "logit")

tweedie(link = "log")

Arguments

link

(character) link function for the conditional mean ("log", "logit", "probit", "inverse", "cloglog", or "identity")

Value

returns a list with (at least) components

family

length-1 character vector giving the family name

link

length-1 character vector specifying the link function

variance

a function of either 1 (mean) or 2 (mean and dispersion parameter) arguments giving a value proportional to the predicted variance (scaled by sigma(.))

Details

If specified, the dispersion model uses a log link. Denoting the dispersion parameter as phi=exp(eta) (where eta is the linear predictor from the dispersion model) and the predicted mean as mu:

gaussian

(from base R): constant variance=phi

Gamma

(from base R) phi is the shape parameter, i.e variance=mu*phi

nbinom2

variance increases quadratically with the mean (Hardin & Hilbe 2007), i.e. variance=mu*(1+mu/phi)

nbinom1

variance increases linearly with the mean (Hardin & Hilbe 2007), i.e. variance=mu*(1+phi)

compois

is the Conway-Maxwell Poisson parameterized with the exact mean which differs from the COMPoissonReg package (Sellers & Lotze 2015)

genpois

is the generalized Poisson distribution

beta

follows the parameterization of Ferrari and Cribari-Neto (2004) and the betareg package, i.e. variance=mu*(1-mu)

References

  • Ferrari SLP, Cribari-Neto F (2004). "Beta Regression for Modelling Rates and Proportions." J. Appl. Stat. 31(7), 799-815.

  • Hardin JW & Hilbe JM (2007). "Generalized linear models and extensions." Stata Press.

  • Sellers K & Lotze T (2015). "COMPoissonReg: Conway-Maxwell Poisson (COM-Poisson) Regression". R package version 0.3.5. https://CRAN.R-project.org/package=COMPoissonReg