code: public static function ZTEST($dataSet, $m0, $sigma = null)
      {
          $dataSet = Functions::flattenArrayIndexed($dataSet);
          $m0 = Functions::flattenSingleValue($m0);
          $sigma = Functions::flattenSingleValue($sigma);
  
          if ($sigma === null) {
              $sigma = self::STDEV($dataSet);
          }
          $n = count($dataSet);
  
          return 1 - self::NORMSDIST((self::AVERAGE($dataSet) - $m0) / ($sigma / sqrt($n)));
      }
docs: ZTEST.
  
  Returns the Weibull distribution. Use this distribution in reliability
  analysis, such as calculating a device's mean time to failure.
  
  @param float $dataSet
  @param float $m0 Alpha Parameter
  @param float $sigma Beta Parameter
  
  @return float