# std

Standard deviation of probability distribution

## Description

example

s = std(pd) returns the standard deviation s of the probability distribution pd.

## Examples

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Load the sample data. Create a vector containing the first column of students' exam grade data.

Fit a normal distribution object to the data.

pd = fitdist(x,'Normal')
pd =
NormalDistribution

Normal distribution
mu = 75.0083   [73.4321, 76.5846]
sigma =  8.7202   [7.7391, 9.98843]

Compute the standard deviation of the fitted distribution.

s = std(pd)
s = 8.7202

For a normal distribution, the standard deviation is equal to the parameter sigma.

Create a Weibull probability distribution object.

pd = makedist('Weibull','A',5,'B',2)
pd =
WeibullDistribution

Weibull distribution
A = 5
B = 2

Compute the standard deviation of the distribution.

s = std(pd)
s = 2.3163

Create a triangular distribution object.

pd = makedist('Triangular','A',-3,'B',1,'C',3)
pd =
TriangularDistribution

A = -3, B = 1, C = 3

Compute the standard deviation of the distribution.

s = std(pd)
s = 1.2472

Load the sample data. Create a vector containing the first column of students’ exam grade data.

Create a probability distribution object by fitting a kernel distribution to the data.

pd = fitdist(x,'Kernel')
pd =
KernelDistribution

Kernel = normal
Bandwidth = 3.61677
Support = unbounded

Compute the standard deviation of the fitted distribution.

s = std(pd)
s = 9.4069

## Input Arguments

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Probability distribution, specified as one of the probability distribution objects in the following table.

Distribution ObjectFunction or App Used to Create Probability Distribution Object
BinomialDistributionmakedist, fitdist, Distribution Fitter
BirnbaumSaundersDistributionmakedist, fitdist, Distribution Fitter
BurrDistributionmakedist, fitdist, Distribution Fitter
ExponentialDistributionmakedist, fitdist, Distribution Fitter
ExtremeValueDistributionmakedist, fitdist, Distribution Fitter
GeneralizedExtremeValueDistributionmakedist, fitdist, Distribution Fitter
GeneralizedParetoDistributionmakedist, fitdist, Distribution Fitter
HalfNormalDistributionmakedist, fitdist, Distribution Fitter
InverseGaussianDistributionmakedist, fitdist, Distribution Fitter
KernelDistributionfitdist, Distribution Fitter
LogisticDistributionmakedist, fitdist, Distribution Fitter
LoglogisticDistributionmakedist, fitdist, Distribution Fitter
LognormalDistributionmakedist, fitdist, Distribution Fitter
LoguniformDistributionmakedist
MultinomialDistributionmakedist
NakagamiDistributionmakedist, fitdist, Distribution Fitter
NegativeBinomialDistributionmakedist, fitdist, Distribution Fitter
NormalDistributionmakedist, fitdist, Distribution Fitter
PiecewiseLinearDistributionmakedist
PoissonDistributionmakedist, fitdist, Distribution Fitter
RayleighDistributionmakedist, fitdist, Distribution Fitter
RicianDistributionmakedist, fitdist, Distribution Fitter
StableDistributionmakedist, fitdist, Distribution Fitter
tLocationScaleDistributionmakedist, fitdist, Distribution Fitter
TriangularDistributionmakedist
UniformDistributionmakedist
WeibullDistributionmakedist, fitdist, Distribution Fitter

## Output Arguments

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Standard deviation of the probability distribution, returned as a nonnegative scalar value.

## Version History

Introduced in R2013a