Uses an indirect method based on truncated quantile-quantile plots to estimate reference limits from routine laboratory data. The principle of the method was developed by Robert G Hoffmann (1963) <doi:10.1001/jama.1963.03060110068020> and modified by Georg Hoffmann and colleagues (2015) <doi:10.1515/labmed-2015-0104>, (2020) <doi:10.1515/labmed-2020-0005>, and (2022) <doi:10.1007/978-3-031-15509-3_31>.

Provides tools for importing and working with bibliographic
    references. It greatly enhances the 'bibentry' class by providing a class
    'BibEntry' which stores 'BibTeX' and 'BibLaTeX' references, supports 'UTF-8'
    encoding, and can be easily searched by any field, by date ranges, and by
    various formats for name lists (author by last names, translator by full names,
    etc.). Entries can be updated, combined, sorted, printed in a number of styles,
    and exported. 'BibTeX' and 'BibLaTeX' '.bib' files can be read into 'R' and
    converted to 'BibEntry' objects. Interfaces to 'NCBI Entrez', 'CrossRef', and
    'Zotero' are provided for importing references and references can be created
    from locally stored 'PDF' files using 'Poppler'. Includes functions for citing
    and generating a bibliography with hyperlinks for documents prepared with
    'RMarkdown' or 'RHTML'.

Takes formulas including random-effects components (formatted as in 'lme4', 'glmmTMB', etc.) and processes them. Includes various helper functions.

An R package for estimating conditional multivariate reference regions. 
    The reference region is non parametrically estimated using a kernel density estimator.
    Covariates effects on the multivariate response means vector and variance-covariance
    matrix, thus on the region shape, are estimated by flexible additive predictors. 
    Continuous covariates non linear effects might be estimated using penalized splines smoothers.
    Confidence intervals for the covariates estimated effects might be derived from
    bootstrap resampling. Kernel density bandwidth can be estimated with different methods, including
    a method that optimize the region coverage. Numerical, and graphical, summaries
    can be obtained by the user in order to evaluate reference region performance with real data.
    Full mathematical details can be found in <doi:10.1002/sim.9163> and <doi:10.1007/s00477-020-01901-1>.