Compute the unbiased sample variance over all iterated values.
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> Compute the [unbiased sample variance][sample-variance] over all [iterated][mdn-iterator-protocol] values.
The [unbiased sample variance][sample-variance] is defined as
``bash`
npm install @stdlib/stats-iter-variance
`javascript`
var itervariance = require( '@stdlib/stats-iter-variance' );
#### itervariance( iterator\[, mean] )
Computes the [unbiased sample variance][sample-variance] over all [iterated][mdn-iterator-protocol] values.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0 ] );
var s2 = itervariance( arr );
// returns 1.0
`
If the mean is already known, provide a mean argument.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var arr = array2iterator( [ 2.0, 1.0, 3.0 ] );
var s2 = itervariance( arr, 2.0 );
// returns ~0.67
`
- If an iterated value is non-numeric (including NaN), the returned [iterator][mdn-iterator-protocol] returns NaN. If non-numeric iterated values are possible, you are advised to provide an [iterator][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.
`javascript
var runif = require( '@stdlib/random-iter-uniform' );
var itervariance = require( '@stdlib/stats-iter-variance' );
// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
'seed': 1234,
'iter': 100
});
// Compute the unbiased sample variance:
var s2 = itervariance( rand );
// returns
console.log( 'Variance: %d.', s2 );
`
*
- [@stdlib/stats-iter/mean][@stdlib/stats/iter/mean]: compute the arithmetic mean over all iterated values.
- [@stdlib/stats-iter/stdev][@stdlib/stats/iter/stdev]: compute the corrected sample standard deviation over all iterated values.
*
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For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
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---
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Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/stats-iter-variance/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-iter-variance/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-iter-variance/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-iter-variance/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-iter-variance/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-iter-variance/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-iter-variance/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-iter-variance/main/LICENSE
[sample-variance]: https://en.wikipedia.org/wiki/Variance
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
[@stdlib/stats/iter/mean]: https://www.npmjs.com/package/@stdlib/stats-iter-mean
[@stdlib/stats/iter/stdev]: https://www.npmjs.com/package/@stdlib/stats-iter-stdev