PdfRpt.Aggregates.Numbers.Variance.groupVariance C# (CSharp) Method

        private void groupVariance(double cellValue)
        {
            _groupRowValues.Add(cellValue);

            _groupSum += cellValue;
            var mean = (_groupSum / _groupRowDataNumber);

            double variance = 0;
            foreach (var item in _groupRowValues)
            {
                variance = variance + Math.Pow((item - mean), 2);
            }

            _groupVariance = variance / _groupRowDataNumber;
        }