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# Mean

> [Bernoulli][bernoulli-distribution] distribution [expected value][expected-value].

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<section class="intro">

The [expected value][expected-value] for a [Bernoulli][bernoulli-distribution] random variable is

<!-- <equation class="equation" label="eq:bernoulli_expectation" align="center" raw="\mathbb{E}\left[ X \right] = p" alt="Expected value for a Bernoulli distribution."> -->

<div class="equation" align="center" data-raw-text="\mathbb{E}\left[ X \right] = p" data-equation="eq:bernoulli_expectation">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@591cf9d5c3a0cd3c1ceec961e5c49d73a68374cb/lib/node_modules/@stdlib/stats/base/dists/bernoulli/mean/docs/img/equation_bernoulli_expectation.svg" alt="Expected value for a Bernoulli distribution.">
    <br>
</div>

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where `p` is the success probability.

</section>

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<section class="usage">

## Usage

```javascript
var mean = require( '@stdlib/stats/base/dists/bernoulli/mean' );
```

#### mean( p )

Returns the [expected value][expected-value] of a [Bernoulli][bernoulli-distribution] distribution with success probability `p`.

```javascript
var v = mean( 0.1 );
// returns 0.1

v = mean( 0.5 );
// returns 0.5
```

If provided a success probability `p` outside of `[0,1]`, the function returns `NaN`.

```javascript
var v = mean( NaN );
// returns NaN

v = mean( 1.5 );
// returns NaN

v = mean( -1.0 );
// returns NaN
```

</section>

<!-- /.usage -->

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</section>

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## Examples

<!-- eslint no-undef: "error" -->

```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var mean = require( '@stdlib/stats/base/dists/bernoulli/mean' );

var v;
var i;
var p;

for ( i = 0; i < 10; i++ ) {
    p = randu();
    v = mean( p );
    console.log( 'p: %d, E(X;p): %d', p.toFixed( 4 ), v.toFixed( 4 ) );
}
```

</section>

<!-- /.examples -->

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</section>

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</section>

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<section class="links">

[bernoulli-distribution]: https://en.wikipedia.org/wiki/Bernoulli_distribution

[expected-value]: https://en.wikipedia.org/wiki/Expected_value

</section>

<!-- /.links -->
