Tools

ferx-core fits one model to one dataset. Everything that calls fit() more than once — resampling, screening, searching a model space — lives in ferx-tools and is exposed as a ferx <tool> subcommand. Each tool carries a maturity tag; see Feature Maturity for what the tags mean.

Uncertainty

  • Bootstrap — non-parametric case bootstrap: resample subjects with replacement, refit, and read bias, standard errors and confidence intervals off the spread of the estimates. PsN bootstrap feature parity.

Covariate screening

  • GAM covariate screening — rank covariate–ETA pairs by ΔAIC on the EBEs before paying for a stepwise search. The ferx equivalent of Xpose4’s xpose.gam().

Model-space searches

All searches read the same .ferxsearch configuration file, whose search space is written in Pharmpy’s Model Feature Language (MFL).

  • Search configuration — the .ferxsearch TOML file, the MFL grammar ferx accepts, and the coverage table of what is and is not supported.
  • Covariate search — stepwise covariate modelling: PsN scm forward / forward-then-backward and Pharmpy covsearch, plus allometric scaling.
  • Structural model search — Pharmpy modelsearch over absorption route, peripheral compartments, transit compartments and lag time.
  • Residual-error search — Pharmpy ruvsearch over the [error_model] block, tested by likelihood ratio.
  • Variability-structure search — Pharmpy iivsearch: which parameters carry an η and how the omegas are blocked.
  • Inter-occasion variability search — Pharmpy iovsearch: which parameters carry an occasion-level κ.

End to end

  • Automatic model development — Pharmpy amd: the searches above run in order from one .ferxsearch file, each seeded from the model the last one selected, reported as one object.