brms (version 2.9.0)

gr: Set up basic grouping terms in brms

Description

Function used to set up a basic grouping term in brms. The function does not evaluate its arguments -- it exists purely to help set up a model with grouping terms. gr is called implicitly inside the package and there is usually no need to call it directly.

Usage

gr(..., by = NULL, dist = "gaussian")

Arguments

...

One or more terms containing grouping factors.

by

An optional factor variable, specifying sub-populations of the groups. For each level of the by variable, a separate variance-covariance matrix will be fitted. Levels of the grouping factor must be nested in levels of the by variable.

dist

Name of the distribution of the group-level effects. Currently "gaussian" is the only option.

See Also

brmsformula

Examples

# NOT RUN {
# model using basic lme4-style formula
fit1 <- brm(count ~ Trt + (1|patient), data = epilepsy)
summary(fit1)

# equivalent model using 'gr' which is called anyway internally
fit2 <- brm(count ~ Trt + (1|gr(patient)), data = epilepsy)
summary(fit2)

# include Trt as a by variable
fit3 <- brm(count ~ Trt + (1|gr(patient, by = Trt)), data = epilepsy)
summary(fit3)
# }
# NOT RUN {
# }