Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Statistical.php
public static function CONFIDENCE($alpha, $stdDev, $size)
    {
        $alpha = Functions::flattenSingleValue($alpha);
        $stdDev = Functions::flattenSingleValue($stdDev);
        $size = floor(Functions::flattenSingleValue($size));

        if ((is_numeric($alpha)) && (is_numeric($stdDev)) && (is_numeric($size))) {
            if (($alpha <= 0) || ($alpha >= 1)) {
                return Functions::NAN();
            }
            if (($stdDev <= 0) || ($size < 1)) {
                return Functions::NAN();
            }

            return self::NORMSINV(1 - $alpha / 2) * $stdDev / sqrt($size);
        }

        return Functions::VALUE();
    }
public static function CONFIDENCE($alpha, $stdDev, $size)
    {
        $alpha = Functions::flattenSingleValue($alpha);
        $stdDev = Functions::flattenSingleValue($stdDev);
        $size = floor(Functions::flattenSingleValue($size));

        if ((is_numeric($alpha)) && (is_numeric($stdDev)) && (is_numeric($size))) {
            if (($alpha <= 0) || ($alpha >= 1)) {
                return Functions::NAN();
            }
            if (($stdDev <= 0) || ($size < 1)) {
                return Functions::NAN();
            }

            return self::NORMSINV(1 - $alpha / 2) * $stdDev / sqrt($size);
        }

        return Functions::VALUE();
    }
public static function CONFIDENCE ( $ alpha , $ stdDev , $ size ) { $ alpha = Functions :: flattenSingleValue ( $ alpha ) ; $ stdDev = Functions :: flattenSingleValue ( $ stdDev ) ; $ size = floor ( Functions :: flattenSingleValue ( $ size ) ) ; if ( ( is_numeric ( $ alpha ) ) && ( is_numeric ( $ stdDev ) ) && ( is_numeric ( $ size ) ) ) { if ( ( $ alpha <= 0 ) || ( $ alpha >= 1 ) ) { return Functions :: NAN ( ) ; } if ( ( $ stdDev <= 0 ) || ( $ size < 1 ) ) { return Functions :: NAN ( ) ; } return self :: NORMSINV ( 1 - $ alpha / 2 ) * $ stdDev / sqrt ( $ size ) ; } return Functions :: VALUE ( ) ; }
CONFIDENCE.

Returns the confidence interval for a population mean

@param float $alpha
@param float $stdDev Standard Deviation
@param float $size

@return float
CONFIDENCE .