# tablepress/3.4/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Confidence.php

TablePress – Tables in WordPress made easy, version 3.4. 55 lines.

- Page: https://pluginprobe.com/plugins/tablepress/3.4/code/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Confidence.php
- Raw: https://pluginprobe.com/plugins/tablepress/3.4/raw/libraries/vendor/PhpSpreadsheet/Calculation/Statistical/Confidence.php
- Modified: 2025-08-26T04:06:14+00:00

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```php
<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Statistical;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Functions;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;

class Confidence
{
	use ArrayEnabled;

	/**
	 * CONFIDENCE.
	 *
	 * Returns the confidence interval for a population mean
	 *
	 * @param mixed $alpha As a float
	 *                      Or can be an array of values
	 * @param mixed $stdDev Standard Deviation as a float
	 *                      Or can be an array of values
	 * @param mixed $size As an integer
	 *                      Or can be an array of values
	 *
	 * @return array<mixed>|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function CONFIDENCE($alpha, $stdDev, $size)
	{
		if (is_array($alpha) || is_array($stdDev) || is_array($size)) {
			return self::evaluateArrayArguments([self::class, __FUNCTION__], $alpha, $stdDev, $size);
		}

		try {
			$alpha = StatisticalValidations::validateFloat($alpha);
			$stdDev = StatisticalValidations::validateFloat($stdDev);
			$size = StatisticalValidations::validateInt($size);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		if (($alpha <= 0) || ($alpha >= 1) || ($stdDev <= 0) || ($size < 1)) {
			return ExcelError::NAN();
		}
		/** @var float $temp */
		$temp = Distributions\StandardNormal::inverse(1 - $alpha / 2);

		/** @var float */
		$result = Functions::scalar($temp * $stdDev / sqrt($size));

		return $result;
	}
}

```