NErler

# Compare proportions in categorical variables between observed and imputed data
# visually (using ggplot)
#
# Parameters:
# x: mids object (from mice)
# formula: formula describing which variables to plot
# facet: either "wrap" for facet_wrap or "grid" for facet_grid
# ...: additional parameters passed to theme()
#
# Note: if the formula is not specified, all imputed categorical variables are