social_learning.ListExtensions.Stdev C# (CSharp) Method

        public static double Stdev(this IEnumerable<double> data)
        {
            if (data.Count() < 2)
                return 0;

            double avg = data.Average();
            double numerator = 0;
            foreach (double d in data)
                numerator += (d - avg) * (d - avg);

            double variance = numerator / (double)(data.Count() - 1);

            return Math.Sqrt((double)variance);
        }