Extending the Range of Functions for Probability Distributions

A consistent, unified and extensible framework for estimation of parameters for probability distributions, including parameter estimation procedures that allow for weighted samples; the current set of distributions included are: the standard beta, The four-parameter beta, Burr, gamma, Gumbel, Johnson SB and SU, Laplace, logistic, normal, symmetric truncated normal, truncated normal, symmetric-reflected truncated beta, standard symmetric-reflected truncated beta, triangular, uniform, and Weibull distributions; decision criteria and selections based on these decision criteria.


ExtDist: Extending the Range of Functions for Probability Distributions

A consistent, unified and extensible framework for estimation of parameters for probability distributions, including parameter estimation procedures that allow for weighted samples; the current set of distributions included are: the standard beta, the four-parameter beta, Burr, gamma, Gumbel, Johnson SB and SU, Laplace, logistic, normal, symmetric truncated normal, truncated normal, symmetric-reflected truncated beta, standard symmetric-reflected truncated beta, triangular, uniform, and Weibull distributions; decision criteria and selections based on these decision criteria.

Online version of documentation is available at GitHub Pages.

Notable updates

0.7-4 (2025-09-17)

Fixed a couple of errors in "Normal_trunc_ab" parameter estimation

0.7-1 (2023-01-16)

Long-standing bug in Weibull and gamma distributions was fixed:

  • for gamma distribution, scale parameter was passed as a rate in stats::*gamma calls

  • for Weibull distribution, stats::*gamma was called instead of stats::*weibull

Reference manual

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install.packages("ExtDist")

0.7-4 by Oleksii Nikolaienko, a year ago


https://github.com/oleksii-nikolaienko/ExtDist


Report a bug at https://github.com/oleksii-nikolaienko/ExtDist/issues


Browse source code at https://github.com/cran/ExtDist


Authors: Haizhen Wu [aut] , A. Jonathan R. Godfrey [aut] , Kondaswamy Govindaraju [aut] , Sarah Pirikahu [aut] , Oleksii Nikolaienko [cre, ctb]


Documentation:   PDF Manual  


GPL (>= 2) license


Imports numDeriv, optimx

Suggests ggplot2, knitr, PerformanceAnalytics, stats, SuppDists, truncdist, VGAM, xtable, graphics, utils, rmarkdown


Imported by BayesPower, kko, noisemodel, tidysynthesis.

Suggested by fitteR.


See at CRAN