Confidence.php

Go to the documentation of this file.

<?php
 
namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical;
 
use PhpOffice\PhpSpreadsheet\Calculation\Exception;
use PhpOffice\PhpSpreadsheet\Calculation\Functions;
 
class Confidence
{
    public static function CONFIDENCE($alpha, $stdDev, $size)
    {
        $alpha = Functions::flattenSingleValue($alpha);
        $stdDev = Functions::flattenSingleValue($stdDev);
        $size = Functions::flattenSingleValue($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 Functions::NAN();
        }
 
        return Distributions\StandardNormal::inverse(1 - $alpha / 2) * $stdDev / sqrt($size);
    }
}