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DistributionParameterQ[dist]

yields True if dist is a valid distribution, and yields False otherwise.

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Examples  
Basic Examples  
Scope  
Applications  
Properties & Relations  
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DistributionParameterQ

DistributionParameterQ[dist]

yields True if dist is a valid distribution, and yields False otherwise.

Details

  • DistributionParameterQ checks that numeric parameters meet parameter assumptions for the input distribution dist and assumes symbolic parameters are valid.
  • DistributionParameterQ issues a message when it encounters an invalid parameter.

Examples

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Basic Examples  (1)

Check a normal distribution with valid parameters:

Wolfram Language code: DistributionParameterQ[NormalDistribution[μ, σ]]

A normal distribution with invalid standard deviation:

Wolfram Language code: DistributionParameterQ[NormalDistribution[0, I]]

Scope  (3)

Test distributions with combinations of numeric and symbolic parameters:

Wolfram Language code: gammas = Table[GammaDistribution[a, b], {a, {α, 1}}, {b, {β, 2}}]//Flatten
Wolfram Language code: Table[{dist, DistributionParameterQ[dist]}, {dist, gammas}]//Grid

Check valid univariate and multivariate discrete and continuous distributions:

Wolfram Language code: validDistributions = {ParetoDistribution[k, a], PoissonDistribution[μ], BinormalDistribution[ρ], NegativeMultinomialDistribution[n, {Subscript[p, 1], Subscript[p, 2], Subscript[p, 3]}]};
Wolfram Language code: Table[{dist, DistributionParameterQ[dist]}, {dist, validDistributions}]//Grid

Check invalid distributions:

Wolfram Language code: invalidDistributions = {ParetoDistribution[-3, a], PoissonDistribution[I], BinormalDistribution[5], NegativeMultinomialDistribution[n, {Subscript[p, 1], 3, Subscript[p, 3]}]};
Wolfram Language code: Table[{dist, DistributionParameterQ[dist]}, {dist, invalidDistributions}]//Grid

Test a constructed distribution:

Wolfram Language code: tdist = TransformedDistribution[x ^ 3, xPoissonDistribution[μ]];
Wolfram Language code: DistributionParameterQ[tdist]

A data distribution:

Wolfram Language code: ddist = EmpiricalDistribution[Range[10]];
Wolfram Language code: DistributionParameterQ[ddist]

Applications  (1)

Define a function for valid distributions:

Wolfram Language code: cubedMean[dist_ ? DistributionParameterQ] := Mean[dist] ^ 3

The function evaluates on a distribution:

Wolfram Language code: cubedMean[BetaDistribution[α, β]]

It returns unevaluated for other inputs:

Wolfram Language code: cubedMean[expr]

Properties & Relations  (1)

DistributionParameterQ assumes symbolic parameters are valid:

Wolfram Language code: DistributionParameterQ[BinomialDistribution[n, p]]

DistributionParameterAssumptions returns conditions on parameters:

Wolfram Language code: DistributionParameterAssumptions[BinomialDistribution[n, p]]

With numeric parameters, the outputs are equivalent:

Wolfram Language code: DistributionParameterQ[BinomialDistribution[20, 1 / 3]]
Wolfram Language code: DistributionParameterAssumptions[BinomialDistribution[20, 1 / 3]]
Wolfram Research (2010), DistributionParameterQ, Wolfram Language function, https://reference.wolfram.com/language/ref/DistributionParameterQ.html.

Text

Wolfram Research (2010), DistributionParameterQ, Wolfram Language function, https://reference.wolfram.com/language/ref/DistributionParameterQ.html.

CMS

Wolfram Language. 2010. "DistributionParameterQ." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/DistributionParameterQ.html.

APA

Wolfram Language. (2010). DistributionParameterQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/DistributionParameterQ.html

BibTeX

@misc{reference.wolfram_2026_distributionparameterq, author="Wolfram Research", title="{DistributionParameterQ}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/DistributionParameterQ.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_distributionparameterq, organization={Wolfram Research}, title={DistributionParameterQ}, year={2010}, url={https://reference.wolfram.com/language/ref/DistributionParameterQ.html}, note=[Accessed: 13-June-2026]}