Distributions
A data-driven catalog. The Core families are always available; each engineering major adds a tailored pack. Free covers the Core and the Free additionals; numerically advanced families are Pro.
Every family WhichDist can fit, drawn from its own probability curve. Shapes are illustrative — the add-in fits real parameters to your data. Free families ship with the Core catalog and free major packs; Pro unlocks the advanced numerics.
Normal
FreeContinuous · μ, σ
Symmetric measurement error, sums of many small effects.
Exponential
FreeContinuous · λ (rate)
Time between random arrivals; memoryless lifetimes.
Weibull (2-param)
FreeContinuous · k, λ
Reliability & failure times; flexible hazard shape.
Lognormal
FreeContinuous · μ, σ
Right-skewed positive data; multiplicative processes.
Gamma
FreeContinuous · k, θ
Waiting times, rainfall totals, aggregated service.
Uniform
FreeContinuous · a, b
Equal likelihood across a range; rough priors.
Triangular
FreeContinuous · a, c, b
Expert estimates with min / mode / max only.
Beta
FreeContinuous · α, β
Proportions and rates bounded on [0, 1].
Poisson
FreeDiscrete · λ
Counts of rare events per interval.
Binomial
FreeDiscrete · n, p
Successes in a fixed number of trials.
Empirical
FreeReference · sample
Non-parametric fallback — always offered.
Erlang
FreeContinuous · k (int), θ
Sum of k exponential phases; service networks.
Geometric
FreeDiscrete · p
Trials until the first success.
Negative Binomial
FreeDiscrete · r, p
Over-dispersed counts; trials until r successes.
Rayleigh
FreeContinuous · σ
Magnitudes of 2-D vectors; wind speed, signal envelope.
Gumbel
FreeContinuous · μ, β
Extreme maxima — floods, peak loads.
Pareto
FreeContinuous · xₘ, α
Heavy-tailed sizes; wealth, file sizes, losses.
GEV
FreeContinuous · μ, σ, ξ
Generalised extreme value for block maxima.
Student’s t
FreeContinuous · ν
Heavier-tailed than Normal; small-sample noise.
Log-logistic
FreeContinuous · α, β
Survival & hydrology; skewed with heavier tail.
Chi-squared
FreeContinuous · k
Sums of squared normals; variance & GoF tests.
Inverse Gaussian
ProContinuous · μ, λ
First-passage times; skewed positive lifetimes.
Weibull (3-param)
ProContinuous · k, λ, γ
Weibull with a failure-free threshold shift.
Pearson III
ProContinuous · shape, scale, loc
Shifted gamma; flood-frequency analysis.
Rice
ProContinuous · ν, σ
Signal-plus-noise envelope; MRI, comms.
Mixture of 2 Normals
ProContinuous · w, μ₁,σ₁, μ₂,σ₂
Two overlapping regimes / sub-populations.
Hypergeometric
ProDiscrete · N, K, n
Draws without replacement; sampling QA.
Full catalog by tier & major
Core (Free)
Continuous
Normal, Exponential, Weibull (2-param), Lognormal, Gamma, Uniform, Triangular, Beta
Discrete
Poisson, Binomial
Reference
Empirical (non-parametric, always offered)
Free major-pack additionals
IE / OR / Simulation
Erlang, Geometric, Negative Binomial, Discrete Uniform
Mechanical / Reliability
Rayleigh, Gumbel, Pareto
Civil / Environmental
GEV, Fréchet, Truncated Normal
Electrical / Telecom
Rayleigh, Erlang, Pareto, Student’s t
Chemical / Process
Log-logistic, Chi-squared
Quality / Manufacturing
Negative Binomial, Geometric, Student’s t
Pro additionals
Advanced families
Inverse Gaussian, Weibull (3-param), Pearson III, Log-Pearson III, Rice, Hypergeometric, Truncated Exponential, Mixture of 2 Exponentials, Mixture of 2 Normals