Fit a multivariate longitudinal sub-model with mixed continuous/ordinal biomarkers (Gaussian-copula extension)

Internal counterpart to longitudinalSubGaussian(), used by the longitudinalSub dispatcher whenever at least one biomarker is categorical/ordinal. Each biomarker is still fit on its own first, exactly following longitudinalSubGaussian()'s IFM strategy: continuous biomarkers via nlme::lme() (byte-identical code path to longitudinalSubGaussian()), ordinal biomarkers via fit_marginal_ordinal() (ordinal::clmm() with a probit link). The resulting per-biomarker fixed effects, thresholds, and random-effects covariance blocks seed the same D/beta/sigma2 bookkeeping longitudinalSubGaussian() builds, which is then handed to longitudinalSubVarCopula() (rather than longitudinalSubVar()) to jointly re-estimate D across all biomarkers, including the ordinal ones' latent Gaussian scores.

Usage

longitudinalSubCopula(
  data_fit_all,
  long_sub_fixed,
  long_sub_random,
  biomarker_type,
  M
)