surveillance (version 1.12.1)

hhh4_formula: Specify Formulae in a Random Effects HHH Model

Description

The special functions fe and ri are used to specify unit-specific effects of covariates and random intercept terms, respectively, in the component formulae of hhh4.

Usage

fe(x, unitSpecific = FALSE, which = NULL, initial = NULL)

ri(type = c("iid","car"), corr = c("none", "all"), initial.fe = 0, initial.var = -.5, initial.re = NULL)

Arguments

x
an expression like sin(2*pi*t/52) involving the time variable t, or just 1 for an intercept. In general this covariate expression might use any variables contained in the control$data argumen
unitSpecific
logical indicating if the effect of x should be unit-specific. This is a convenient shortcut for which = rep(TRUE, nUnits), where nUnits is the number of units (i.e., columns of the "sts" obj
which
vector of logicals indicating which unit(s) should get an unit-specific parameter. For units with a FALSE value, the effect term for x will be zero in the log-linear predictor. Note especially that setting a
initial
initial values (on internal scale!) for the fixed effects used for optimization. The default (NULL) means to use zeroes.
type
random intercepts either follow an IID or a CAR model.
corr
whether random effects in different components (such as ar and end) should be correlated or not.
initial.fe
initial value for the random intercept mean.
initial.var
initial values (on internal scale!) for the variance components used for optimization.
initial.re
initial values (on internal scale!) for the random effects used for optimization. The default NULL are random numbers from a normal distribution with zero mean and variance 0.001.

encoding

latin1

See Also

addSeason2formula

hhh4 model specifications in vignette("hhh4"), vignette("hhh4_spacetime") or on the help page of hhh4.