factor_invariance.R

plot_measurement_invariance = function(model){
  factor_loadings = parameterEstimates(model) %>%
    rename(estimate = est, low = ci.lower, high = ci.upper) %>% 
    mutate(rhs = factor(rhs, levels = unique(rhs)),
           lhs = factor(lhs, levels = unique(lhs)),
           label = paste(lhs, op, rhs),
           type = case_when(
             op == '=~' ~ 'Loading',
             op == '~~' ~ 'Covariance',
             op == '~1' ~ 'Mean',
             T ~ '???'
           ))
  if(!'group' %in% names(factor_loadings)){
    factor_loadings$group = 'Common'
  }

  ggplot(factor_loadings,
         aes(fct_rev(label), estimate,
             color = factor(group),
             ymin = low, ymax = high)) +
    facet_wrap(~type, scales = 'free') +
    geom_point() +
    geom_errorbar(width=.2) +
    geom_hline(linetype = 'dashed', yintercept = 0) +
    coord_flip() +
    no_legend_bg() +
    labs(x = 'Item', y = 'Weight', color = 'Group')
}

plot_measurement_invariance(model_full) + ggtitle('Full Invariance')
plot_measurement_invariance(model_strict) + ggtitle('Strict Invariance')
plot_measurement_invariance(model_strong) + ggtitle('Strong Invariance')
plot_measurement_invariance(model_weak) + ggtitle('Weak Invariance')
plot_measurement_invariance(model_configural) + ggtitle('Configural Invariance')