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# var

Class: prob.ToolboxFittableParametricDistribution
Package: prob

Variance of probability distribution object

v = var(pd)

## Description

v = var(pd) returns the variance v of the probability distribution pd.

## Input Arguments

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### pd — Probability distributionprobability distribution object

Probability distribution, specified as a probability distribution object. Create a probability distribution object with specified parameter values using makedist. Alternatively, create a probability distribution object by fitting it to data using fitdist or the Distribution Fitting app.

## Output Arguments

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### v — Variancenonnegative scalar value

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

## Examples

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### Variance of a Fitted Distribution

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

```load examgrades;
```

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 variance of the fitted distribution.

`v = var(pd)`
```v =

76.0419```

For a normal distribution, the variance is equal to the square of the parameter sigma.

### Variance of a Skewed Distribution

Create a Weibull probability distribution object.

`pd = makedist('Weibull','a',5,'b',2)`
```pd =

WeibullDistribution

Weibull distribution
A = 5
B = 2```

Compute the variance of the distribution.

`v = var(pd)`
```v =
5.3650```