Specify reference categories for all categorical covariates in the model

The function is a helper function that asks questions and, depending on the answers given by the user, returns the input for the argument refcats in the main analysis functions *_imp.

Usage

set_refcat(data, formula, covars, auxvars = NULL)

Arguments

data

a data.frame

formula

optional; model formula or a list of formulas (used to select subset of relevant columns of data)

covars

optional; vector containing the names of relevant columns of data

auxvars

optional; formula containing the names of relevant columns of data that should be considered additionally to the columns occurring in the formula

Value

Invisibly, the value to be passed to the argument refcats: either one of "first", "last" or "largest", or a named numeric vector with the index of the reference category of each categorical variable.

Details

The arguments formula, covars and auxvars can be used to specify a subset of the data to be considered. If non of these arguments is specified, all variables in data will be considered.

Examples

if (FALSE) { # \dontrun{
# Example 1: set reference categories for the whole dataset and choose
# answer option 3:
set_refcat(data = NHANES)
3

# insert the returned string as argument refcats
mod1 <- lm_imp(SBP ~ age + race + creat + educ, data = NHANES,
               refcats = 'largest')

# Example 2:
# specify a model formula
fmla <- SBP ~ age + gender + race + bili + smoke + alc

# write the output of set_refcat to an object
ref_mod2 <- set_refcat(data = NHANES, formula = fmla)
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2
5
1
1

# enter the output in the model specification
mod2 <- lm_imp(formula = fmla, data = NHANES, refcats = ref_mod2,
               n.adapt = 0)
} # }