This function is used to parse user specified correlation attributes. The correlation attributes need to be in a dataframe to be processed internally. Within the dataframe, there are expected to be 3 columns, 1) names of variable/attributes, 2) the variable/attribute pair for 1, 3) the correlation.
parse_correlation(sim_args)A named list with special model formula syntax. See details and examples for more information. The named list may contain the following:
fixed: This is the fixed portion of the model (i.e. covariates)
random: This is the random portion of the model (i.e. random effects)
error: This is the error (i.e. residual term).
correlate: These are the correlations for random effects and/or fixed effects.