1. DGP4LCF::sim_fcs_init
    Initials values.
  2. DGP4LCF::sim_fcs_results_irregular_6_8
    Results when people have irregularly observed time points (some 6 while others 8).
  3. DGP4LCF::sim_fcs_results_regular_8
    Results when people are observed at common 8 time points.
  4. DGP4LCF::sim_fcs_truth
    Truth of simulated data.